首页 | 本学科首页   官方微博 | 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   47676篇
  免费   3464篇
  国内免费   196篇
耳鼻咽喉   567篇
儿科学   1000篇
妇产科学   966篇
基础医学   6601篇
口腔科学   1003篇
临床医学   4705篇
内科学   10021篇
皮肤病学   1077篇
神经病学   4548篇
特种医学   1961篇
外国民族医学   2篇
外科学   8605篇
综合类   481篇
一般理论   76篇
预防医学   2683篇
眼科学   938篇
药学   2796篇
中国医学   75篇
肿瘤学   3231篇
  2023年   467篇
  2022年   919篇
  2021年   1712篇
  2020年   1017篇
  2019年   1345篇
  2018年   1522篇
  2017年   1024篇
  2016年   1198篇
  2015年   1379篇
  2014年   1869篇
  2013年   2177篇
  2012年   3552篇
  2011年   3501篇
  2010年   1945篇
  2009年   1725篇
  2008年   2728篇
  2007年   2781篇
  2006年   2587篇
  2005年   2404篇
  2004年   2224篇
  2003年   2030篇
  2002年   1861篇
  2001年   524篇
  2000年   515篇
  1999年   536篇
  1998年   430篇
  1997年   339篇
  1996年   253篇
  1995年   247篇
  1994年   208篇
  1993年   213篇
  1992年   365篇
  1991年   337篇
  1990年   310篇
  1989年   271篇
  1988年   258篇
  1987年   242篇
  1986年   234篇
  1985年   261篇
  1984年   216篇
  1983年   204篇
  1982年   168篇
  1981年   158篇
  1980年   169篇
  1979年   182篇
  1978年   150篇
  1977年   136篇
  1976年   135篇
  1974年   142篇
  1973年   122篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Objective: To retrospectively review the management of adenocarcinomain situof the uterine cervix, to determine the outcome of conization versus hysterectomy, and to compare the results achieved by different methods of conization. Methods: We performed a retrospective pathology and chart review of 46 patients with cervical adenocarcinomain situfrom January 1980 to October 1994. Results: Nine patients were managed during the first half of the study period and 37 were managed in the second half. The mean age of patients was 38.4 years (range 25–72). Forty-five of 46 patients were diagnosed as a result of an abnormal Pap smear, although only 19 smears indicated adenocarcinomain situor other glandular abnormalities. Cold knife conization resulted in a 33% rate of positive margins for adenocarcinomain situcompared to 50% for large loop excision of the transformation zone (LLETZ). Among 24 conservatively managed patients with negative conization margins, there have been 2 (8.3%) recurrences of adenocarcinomain situ.Among patients not undergoing hysterectomy as definitive treatment, 1 of 18 (6%) patients undergoing cold knife conization recurred, compared to 4 of 14 (29%) managed with LLETZ, despite a 63.4-month shorter mean follow-up interval for the LLETZ patients. Conclusions: Cold knife conization is associated with a lower rate of recurrence of cervical adenocarcinomain situcompared to LLETZ. We recommend cold knife conization for patients who are not treated with hysterectomy.  相似文献   
102.
The blocking effects of complement-dependent sperm immobilizingantibodies in the sera of infertile women and monoclonal antispermantibodies against humans and mice on fertilization were investigated.The hemizona assay (HZA) and sperm penetration assay (SPA) wereused to study the inhibitory effects of sera from 22 infertilepatients positive for sperm immobilizing antibodies. Use ofthese tests allowed us to differentiate whether the antibodyblocked sperm—zona pellucida tight binding and/or spermpenetration into the ooplasm. The zona pellucida penetrationassay (ZPA) was also used to study the effects of four monoclonalantibodies (mAbs) on human sperm penetration into the zona pellucida.Seven mAbs against murine spermatozoa were tested for theirinhibitory effects on in-vitro fertilization (IVF) and HZA inmice. Of 22 patient sera with sperm immobilizing antibodies,21 (95.5%) inhibited HZA attachment and penetration, whereasthis did not occur in any of 13 patient sera without these antibodies.However, 19 of 22 (86.4%) patient sera with sperm immobilizingantibodies and eight of 13 (61.5%) patient sera without theseantibodies inhibited the SPA. Two (2C6, 1G12) of four mAbs againsthuman spermatozoa showed strong inhibitory effects in all theassays (HZA, ZPA and SPA). One mAb (3B10) did not inhibit HZAbut blocked ZPA and SPA. Another mAb (H6-3C4) seemed to haveno inhibitory effects on fertilization. Two (Vx 5 and Vx 8)of seven mAbs against murine spermatozoa inhibited IVF in micebut did not block mouse HZA. These findings suggest that antispermantibodies block fertilization at specific stages. Some of themmay inhibit sperm capacitation and thus prevent all processesof fertilization that follow. Some other antibodies may notaffect capacitation and sperm binding to zona pellucida butinhibit the acrosome reaction, followed by the blocking of spermpenetration through zona pellucida and ooplasm.  相似文献   
103.
The authors completed a retrospective chart review of the records of all patients identified with diagnoses of mania and schizoaffective disorder, manic type, who underwent electroconvulsive therapy between the years 1973 and 1986 at McLean Hospital. Ten of 18 manic patients (56%) and 3 of 9 schizoaffective patients (33%) experienced meaningful clinical benefit. The authors report the correlation of treatment and patient factors with outcome and review the literature on the convulsive therapy of mania.  相似文献   
104.
105.
106.
In the last 20 years prostitutes, or sex workers, have formed self-help and advocacy organizations in a number of countries that could have an effect on acquired immunodeficiency syndrome (AIDS) and sexually transmitted disease (STD) prevention efforts. It is essential when planning a sex work-related intervention to identify sex workers, clients, or third parties as well as any factors that affect the safety of existing sex and drug use practices. It is important to know where sex workers and clients contact each other, where they go to engage in sex, and the working conditions of sex work establishments. Other considerations include the accessibility of condoms and health care; the impact of laws, regulations, and enforcement practices; and the impact of migration of both sex workers and clients. Many projects have involved members of the target audiences in the assessment as interviewers as well as in the design and implementation of the project. All interventions should include current information, education, and communication consisting of media strategies as well as person-to-person strategies. A combination of sites can help to reach the maximum proportion of the population at risk. Several projects have provided bulk supplies in order to ensure access to condoms at no cost or inexpensively to hotels, bars, brothels and other sex work businesses. Projects have also promoted the use of sterile injection equipment where injecting drug use is common. Functioning outreach and education projects emphasize STD service, such as sensitivity training for health care providers to improve services and diagnostic procedures and to motivate sex workers to utilize the health care system. Voluntary utilization may the boosted by offering STD services in a stationary or mobile clinic in the sex work neighborhoods during the afternoon and early evening and combining them with family planning, primary health care, and child health care.  相似文献   
107.
Penetrating proximity extremity trauma (PPET) was prospectively studied to clarify the role of routine arteriographic evaluation (AG). Over a 24-month period, 135 patients were identified with 152 injuries from PPET. All patients underwent AG and were randomized to either immediate or delayed timing. There were 27 arteriographic abnormalities from these 152 wounds, of which 16 (10.5%) were in major arteries. One acute arteriovenous fistula underwent immediate surgery. The remaining 15 major vessel injuries were nonoperatively observed, including seven cases of segmental arterial narrowing, six intimal flaps, and two small pseudoaneurysms (one of which enlarged and underwent surgical repair after 10 weeks of followup). Nine of the remaining 14 lesions resolved; two improved and three remained clinically unchanged over a mean followup interval of 2.7 months. Shotgun trauma was the mechanism which carried the greatest risk of significant vascular injury. Although "soft" clinical signs were significantly more predictive of vascular injury following PPET than proximity alone (p less than 0.0005), 50% of all injuries to major arteries did not manifest soft signs. No extremity morbidity resulted from delayed AG or from vascular injury management. We conclude from our study population: 1) the natural history of clinically occult arterial injuries was predominantly benign; 2) AG could be safely delayed up to 24 hours; 3) "soft" signs were not clinically useful predictors of vascular injury; and 4) with the exception of shotgun wounds, AG did not appear to be a cost effective screening modality, since detection of a single vascular injury requiring surgery cost $66,420.00.  相似文献   
108.
Astrocytes are capable of regulated release of messenger molecules. Astrocytes cultured from new born rodent brain express a variety of classical presynaptic proteins. We investigated the question whether the capability to express synaptic proteins in culture was a feature only of immature astrocytes, and whether these proteins were also expressed by astrocytes in situ. Experiments were performed with transgenic mice expressing the enhanced green fluorescent protein under the control of the human glial fibrillary acidic protein promoter. Using double fluorescence and astrocytes cultured from 1 to 16 day-old animals we show that the astrocytic expression of synaptic proteins in culture is invariant of the age of donor animals. Culturing can induce the astrocytic expression of specific synaptic proteins such as SV2, synaptophysin and SNAP-25. Astrocytes in brain sections of 1-16 day-old animals revealed a punctuate immunofluorescence for secretory carrier membrane protein (SCAMP), SNAP-23, synaptobrevin II, and cellubrevin, to a minor extent for SNAP-25 and synaptophysin, and none for SV2. Our results demonstrate that cultured astrocytes express synaptic proteins not present in situ. Nevertheless, astrocytic organelles in situ are equipped with molecules that could be involved in regulated exocytosis of messenger substances.  相似文献   
109.
110.
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