如何修改SciFinder API Python代码获取密度、沸点等物性数据

一、获取密度、沸点等物性数据的关键修改 #

默认的substances接口仅返回基础元数据，必须通过fields参数显式指定需要的物性字段，API才会返回对应数据。具体修改点：

• 在请求URL中添加fields参数，多个字段用英文逗号分隔
• 常用物性字段参考：
  • molecularWeight：分子量
  • boilingPoint：沸点
  • density：密度
  • criticalTemperature：临界温度
  • meltingPoint：熔点
  • molecularFormula：分子式

修改后的请求URL示例（移除原代码中重复的冗余请求）：

resp = requests.get(
    'https://helium.cas.org/integration/v1/substances?str=Cc1nc%28n%28n1%29C%28C%29C%29c2cn3c%28n2%29-c4ccc%28cc4OCC3%29c5cnn%28c5%29C%28C%29%28C%29C%28%3DO%29N&strMode=drw&offset=0&length=100&echo=false&strHighlight=false&facet=true&fq=Number%20of%20Components%3A1&fields=casRn,uri,name,molecularWeight,boilingPoint,density,criticalTemperature',
    headers=headers
)

遍历结果时，建议用get()方法访问字段，避免字段不存在时报错：

for substance in json['substances']:
    print(f"CAS号: {substance['casRn']}")
    print(f"名称: {substance['name']}")
    print(f"分子量: {substance.get('molecularWeight', '无数据')}")
    print(f"沸点: {substance.get('boilingPoint', '无数据')}")
    print(f"密度: {substance.get('density', '无数据')}")
    print(f"临界温度: {substance.get('criticalTemperature', '无数据')}")
    print("---")

二、反应检索的实现方法 #

要进行反应检索，需切换到reactions端点，核心修改点：

• 请求URL改为https://helium.cas.org/integration/v1/reactions
• strMode设为rxn（表示反应式搜索）
• 同样用fields指定需要返回的反应字段，比如reactionId、reactionSmiles、reactants、products等

示例代码：

# 搜索生成目标产物的反应
resp_reaction = requests.get(
    'https://helium.cas.org/integration/v1/reactions?str=Cc1nc(n(n1)C(C)C)c2cn3c(n2)-c4ccc(cc4OCC3)c5cnn(c5)C(C)(C)C(=O)N&strMode=rxn&offset=0&length=10&fields=reactionId,reactionSmiles,reactants,products',
    headers=headers
)
if resp_reaction.status_code != 200:
    raise Exception(f'GET reactions/ {resp_reaction.status_code}')
reaction_json = resp_reaction.json()

for reaction in reaction_json['reactions']:
    print(f"反应ID: {reaction['reactionId']}")
    print(f"反应SMILES: {reaction['reactionSmiles']}")
    print(f"反应物: {', '.join([r['name'] for r in reaction['reactants']])}")
    print(f"产物: {', '.join([p['name'] for p in reaction['products']])}")
    print("---")

三、完整修改后的代码 #

import requests

Bearer_Token = "<token>"  # 替换为你的实际Token
headers = {
    'Content-Type': 'application/json',
    'Authorization': f'Bearer {Bearer_Token}'
}

# 1. 获取带物性数据的物质信息
substance_url = (
    'https://helium.cas.org/integration/v1/substances?'
    'str=Cc1nc%28n%28n1%29C%28C%29C%29c2cn3c%28n2%29-c4ccc%28cc4OCC3%29c5cnn%28c5%29C%28C%29%28C%29C%28%3DO%29N&'
    'strMode=drw&offset=0&length=100&echo=false&strHighlight=false&facet=true&'
    'fq=Number%20of%20Components%3A1&'
    'fields=casRn,uri,name,molecularWeight,boilingPoint,density,criticalTemperature,molecularFormula'
)
resp_substance = requests.get(substance_url, headers=headers)
if resp_substance.status_code != 200:
    raise Exception(f'GET substances/ {resp_substance.status_code}')
substance_json = resp_substance.json()

print("=== 物质物性数据 ===")
for substance in substance_json['substances']:
    print(f"CAS号: {substance['casRn']}")
    print(f"名称: {substance['name']}")
    print(f"分子式: {substance.get('molecularFormula', '无数据')}")
    print(f"分子量: {substance.get('molecularWeight', '无数据')}")
    print(f"沸点: {substance.get('boilingPoint', '无数据')}")
    print(f"密度: {substance.get('density', '无数据')}")
    print(f"临界温度: {substance.get('criticalTemperature', '无数据')}")
    print("---")

# 2. 反应检索示例
reaction_url = (
    'https://helium.cas.org/integration/v1/reactions?'
    'str=Cc1nc(n(n1)C(C)C)c2cn3c(n2)-c4ccc(cc4OCC3)c5cnn(c5)C(C)(C)C(=O)N&'
    'strMode=rxn&offset=0&length=10&'
    'fields=reactionId,reactionSmiles,reactants,products'
)
resp_reaction = requests.get(reaction_url, headers=headers)
if resp_reaction.status_code != 200:
    raise Exception(f'GET reactions/ {resp_reaction.status_code}')
reaction_json = resp_reaction.json()

print("\n=== 反应检索结果 ===")
for reaction in reaction_json['reactions']:
    print(f"反应ID: {reaction['reactionId']}")
    print(f"反应SMILES: {reaction['reactionSmiles']}")
    reactant_names = [r['name'] for r in reaction.get('reactants', [])]
    product_names = [p['name'] for p in reaction.get('products', [])]
    print(f"反应物: {', '.join(reactant_names) if reactant_names else '无数据'}")
    print(f"产物: {', '.join(product_names) if product_names else '无数据'}")
    print("---")

内容的提问来源于stack exchange，提问作者Rekton Lee