首页 | 官方网站   微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   67639篇
  免费   6033篇
  国内免费   208篇
医药卫生   73880篇
  2023年   597篇
  2022年   431篇
  2021年   1933篇
  2020年   1462篇
  2019年   2164篇
  2018年   2395篇
  2017年   1870篇
  2016年   2027篇
  2015年   2151篇
  2014年   2723篇
  2013年   3881篇
  2012年   5306篇
  2011年   5319篇
  2010年   3059篇
  2009年   2724篇
  2008年   4399篇
  2007年   4487篇
  2006年   4304篇
  2005年   4055篇
  2004年   3895篇
  2003年   3541篇
  2002年   3207篇
  2001年   543篇
  2000年   429篇
  1999年   512篇
  1998年   743篇
  1997年   566篇
  1996年   484篇
  1995年   473篇
  1994年   380篇
  1993年   368篇
  1992年   265篇
  1991年   242篇
  1990年   214篇
  1989年   179篇
  1988年   179篇
  1987年   125篇
  1986年   148篇
  1985年   149篇
  1984年   158篇
  1983年   156篇
  1982年   190篇
  1981年   181篇
  1980年   137篇
  1979年   88篇
  1978年   97篇
  1977年   84篇
  1976年   93篇
  1975年   69篇
  1974年   72篇
排序方式: 共有10000条查询结果,搜索用时 390 毫秒
991.
992.
Mantle cell lymphoma (MCL) is a type of non‐Hodgkin lymphoma (NHL) with aggressive disease characteristics resulting in multiple relapses after initial treatment. Lenalidomide is an immunomodulatory agent approved in the US for patients with relapsed/refractory MCL following bortezomib based on results from 3 multicenter phase II studies (2 including relapsed/refractory aggressive NHL and 1 focusing on MCL post‐bortezomib). The purpose of this report is to provide longer follow‐up on the MCL‐001 study (follow‐ups were 6.8 [NHL‐002], 7.6 [NHL‐003], and 52.2 [MCL‐001] months). The 206 relapsed MCL patients treated with single‐agent lenalidomide (25 mg/day PO, days 1 to 21 every 28‐days) had a median age of 67 years (63% ≥65 years), 91% with stage III/IV disease, and 50% with ≥4 previous treatment regimens. With a median follow‐up of X, the combined best overall response rate (ORR) was 33% (including 11% with complete remission [CR]/CR unconfirmed CRu). Lenalidomide produced rapid and durable responses with a median time to response of 2.2 months and median duration of response (DOR) of 16.6 months (95% CI: 11.1%‐29.8%). The safety profile was consistent and manageable; myelosuppression was the most common adverse event (AE). Overall, single‐agent lenalidomide showed consistent efficacy and safety in multiple phase II studies of heavily pretreated patients with relapsed/refractory MCL, including those previously treated with bortezomib.  相似文献   
993.
994.
995.
996.
Ifosfamide (IFA) is a potent alkylating antitumoral agent, but its use is limited by neurological side effects. IFA is a racemic mixture of two enantiomeric forms, R‐IFA and S‐IFA with a stereoselective metabolism by CYP3A4 and CYP2B6, leading either to bioactive or to toxic pathways. In three consecutive cases of pediatric patients who exhibited IFA‐induced encephalopathy (IIE), genotyping of clinically relevant single‐nucleotide polymorphisms associated with decreased CYP3A4 and CYP2B6 activities was performed. Genetic investigations revealed the presence of CYP2B6 rs4803419 (C>T) in one patient while the two others carried the CYP2B6*6 allelic variant. All patients carried CYP3A4 wild‐type genotype (CYP3A4*1/*1). Because CYP2B6‐deficient alleles may be responsible for an increased conversion of S‐IFA into neurotoxic metabolites, screening for CYP2B6 polymorphisms may help to avoid IIE and improve clinical outcomes.  相似文献   
997.
998.
999.
We studied the relationship between tinnitus pitch and the audiogram in 195 patients. Patients with tone-like tinnitus reported a higher pitch (mean = 5385 Hz) compared to those with a noise-like quality (mean = 3266 Hz). Those with a flat audiogram were more likely to report: a noise-like tinnitus, a unilateral tinnitus, and have a pitch < 2000 Hz. The average duration of bilateral tinnitus (12 years) was longer than that of unilateral tinnitus (5 years). Older subjects reported a less severe tinnitus handicap questionnaire score. Patients with a notched audiogram often reported a pitch ≤8000 Hz. Subjects with normal hearing up to 8000 Hz tended to have a pitch ≥8000 Hz. We failed to find a relationship between the pitch and the edge of a high frequency hearing loss. Some individuals did exhibit a pitch at the low frequency edge of a hearing loss, but we could find no similar characteristics among these subjects. It is possible that a relationship between pitch and audiogram is present only in certain subgroups.  相似文献   
1000.
Fish stocks experiencing high fishing mortality show a tendency to mature earlier and at a smaller size, which may have a genetic component and therefore long-lasting economic and biological effects. To date, the economic effects of such ecoevolutionary dynamics have not been empirically investigated. Using 70 y of data, we develop a bioeconomic model for Northeast Arctic cod to compare the economic yield in a model in which life-history traits can vary only through phenotypic plasticity with a model in which, in addition, genetic changes can occur. We find that evolutionary changes toward faster growth and earlier maturation occur consistently even if a stock is optimally managed. However, if a stock is managed optimally, the evolutionary changes actually increase economic yield because faster growth and earlier maturation raise the stock’s productivity. The optimal fishing mortality is almost identical for the evolutionary and nonevolutionary model and substantially lower than what it has been historically. Therefore, the costs of ignoring evolution under optimal management regimes are negligible. However, if fishing mortality is as high as it has been historically, evolutionary changes may result in economic losses, but only if the fishery is selecting for medium-sized individuals. Because evolution facilitates growth, the fish are younger and still immature when they are susceptible to getting caught, which outweighs the increase in productivity due to fish spawning at an earlier age.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司    京ICP备09084417号-23

京公网安备 11010802026262号