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   14379篇
  免费   1263篇
  国内免费   81篇
耳鼻咽喉   107篇
儿科学   393篇
妇产科学   249篇
基础医学   2274篇
口腔科学   490篇
临床医学   1553篇
内科学   2818篇
皮肤病学   431篇
神经病学   1156篇
特种医学   770篇
外科学   2157篇
综合类   257篇
一般理论   11篇
预防医学   1307篇
眼科学   189篇
药学   815篇
  2篇
中国医学   4篇
肿瘤学   740篇
  2021年   193篇
  2020年   139篇
  2019年   195篇
  2018年   209篇
  2017年   175篇
  2016年   188篇
  2015年   211篇
  2014年   325篇
  2013年   528篇
  2012年   715篇
  2011年   759篇
  2010年   460篇
  2009年   359篇
  2008年   744篇
  2007年   724篇
  2006年   695篇
  2005年   652篇
  2004年   633篇
  2003年   588篇
  2002年   599篇
  2001年   273篇
  2000年   262篇
  1999年   243篇
  1998年   223篇
  1997年   226篇
  1996年   223篇
  1995年   179篇
  1994年   181篇
  1993年   184篇
  1992年   225篇
  1991年   228篇
  1990年   220篇
  1989年   206篇
  1988年   248篇
  1987年   199篇
  1986年   191篇
  1985年   176篇
  1984年   177篇
  1983年   134篇
  1982年   160篇
  1981年   147篇
  1980年   144篇
  1979年   122篇
  1978年   128篇
  1977年   108篇
  1976年   114篇
  1975年   123篇
  1972年   98篇
  1971年   94篇
  1970年   92篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
Few studies have examined the effects of parental incarceration (PI) on outcomes above and beyond other risk and adverse childhood experiences (ACEs). The objectives of this study were to (1) the associations between PI and mental health problems (attention, externalizing, internalizing, and total behavioral problems) and (2) the mediating role of current socioeconomic status and cumulative ACEs. An observational and cross-sectional design was employed. Analyses included hierarchical multivariable linear regression modeling. The analytic sample included 613 adolescents (11–17?years). On average, youth exposed to PI experienced three times as many ACEs compared with youth unexposed. Youth exposed to PI were more likely to have behavioral problems than their unexposed peers. The main effect for all models was attenuated by current economic hardship as well as exposure to increasing numbers of ACEs. Exposure to PI can be viewed as a marker of accumulative risk for intervention since youth impacted by PI are more likely to experience behavioral difficulties and associated adverse childhood experiences. Due to the associated adversity that impact youth exposed to PI, mental health providers need to be able to identify and screen for symptoms associated with trauma.  相似文献   
2.
Objectives: There is a paucity of reporting on surgical outcomes of isolated posterior cruciate ligament reconstruction (PCLR). We hypothesize that isolated PCL injuries failing nonoperative treatment achieve good outcomes and are able to return to sport following PCLR.

Methods: A retrospective analysis was performed to identify patients with isolated PCL injuries that underwent reconstruction between 2001 and 2014. Patients with multi-ligamentous injury or another concomitant knee pathology were excluded. Medical records were reviewed for demographic, clinical and operative data. Patients were contacted for administration of a telephone-based questionnaire which included the International Knee Documentation Committee (IKDC) Subjective Knee Evaluation form, Lysholm-Tegner scales, Marx activity scale (MAS), return to sport status, and patient satisfaction instruments.

Results: A total of 15 isolated PCL reconstructions in 14 patients with a mean age of 27.5 years (range 17–43) met the study inclusion criteria; mean follow up was 6.3 years (range 1.4–15.2). Pre-operatively, the primary complaint was knee instability in all patients; on physical examination, lack of a firm end point during posterior drawer testing was found in 93% (14/15) of the knees. In total, 12 of 15 knees underwent transtibial, single-bundle PCLR and three of 15 underwent tibial inlay, double bundle PCLR. Graft types included: quadriceps autograft (7/15), Achilles allograft (6/15), and hamstring autograft (2/15). There were no graft failures in our patient cohort. At most recent follow up the mean scores respectively on the IKDC form, Lysholm-Tegner scales and MAS were (standard deviation): 77.3 (16.5), 83.1 (17.9), 6.13 (2.6), and 7.1 (6.0). All fourteen patients were athletes prior to their injury and 79% (11/14) returned to sport and overall patient satisfaction was 9.2/10.

Conclusions: Isolated PCLR provides good outcomes at mean medium-term follow up with restoration of function, high rate of return to sport and overall patient satisfaction.  相似文献   

3.
Annals of Surgical Oncology - The role of sentinel lymph node biopsy (SLNB) when ductal carcinoma in situ with microinvasion (DCISM) is identified on core biopsy is unclear. Our aim was to assess...  相似文献   
4.
5.
Coronary magnetic resonance angiography (CMRA) is a technique in clinical evolution. Current clinical applications include assessment for coronary anomalies, aneurysms, bypass graft patency, and, in experienced centers, the exclusion of proximal and multivessel coronary artery disease (CAD). As local expertise increases and more extensive multicenter data become available, additional applications will be established. CMRA promises to supplement and in some cases obviate the need for X-ray contrast angiography, and to expand our understanding of the pathophysiology of CAD. Zusammenfassung Die Magnetresonanzangiographie der Koronargefäße (CMRA) ist eine sich ständig weiterentwickelnde Technik. Etablierte Anwendungen sind zurzeit die Beurteilung von koronaren Anomalien, Aneurysmen und der Durchgängigkeit von Bypasses. Auch der Ausschluss proximaler Koronarstenosen und einer koronaren Mehrgefäßerkrankung ist in einigen spezialisierten Zentren möglich. Mit zunehmender Erfahrung der jeweiligen Anwender und der Verfügbarkeit von Ergebnissen großer multizentrischer Studien können zukünftig weitere klinische Anwendungen etabliert werden. In der Zukunft könnte die CMRA ergänzende Informationen zur Indikationsstellung einer konventionellen Röntgenangiographie bringen und in einigen Fällen diese Untersuchung sogar ersetzen. Die CMRA wird unseren Einblick in die Pathophysiologie der koronaren Herzerkrankung sicher erweitern.  相似文献   
6.
Ninety-seven inpatients with tardive dyskinesia (average AIMS score = 13), the majority of whom were schizophrenic, were studied. Forty patients were Caucasian, and 57 were African-American. The APOE genotypes of these patients were compared to previously published genotypes of controls and with previously published studies of APOE genotypes in patients with schizophrenia. There were no significant differences in APOE allele frequencies comparing the African-American tardive dyskinesia population and the African-American control groups. In contrast, significant (< 0.05) P values were obtained comparing the Caucasian tardive dyskinesia population to the Caucasian controls, when comparing allele frequencies and genotypic frequencies. This study suggests that Caucasians bearing an APOE2 allele are at increased risk of developing tardive dyskinesia, whereas African-Americans are not. APOE genotype-specific risks of both tardive dyskinesia and Alzheimer's disease that vary across populations could be due to recruitment of patients or controls or could be due to modifying effects of differing genetic or environmental backgrounds. The mechanism by which the APOE2 allele increases risk of tardive dyskinesia is not known. Further information about the mechanisms of increased risk of tardive dyskinesia could result in stratification of prescribing practices weighing the costs of medications against the relative risk of side effects.  相似文献   
7.
A national conference on organ donation after cardiac death (DCD) was convened to expand the practice of DCD in the continuum of quality end-of-life care. This national conference affirmed the ethical propriety of DCD as not violating the dead donor rule. Further, by new developments not previously reported, the conference resolved controversy regarding the period of circulatory cessation that determines death and allows administration of pre-recovery pharmacologic agents, it established conditions of DCD eligibility, it presented current data regarding the successful transplantation of organs from DCD, it proposed a new framework of data reporting regarding ischemic events, it made specific recommendations to agencies and organizations to remove barriers to DCD, it brought guidance regarding organ allocation and the process of informed consent and it set an action plan to address media issues. When a consensual decision is made to withdraw life support by the attending physician and patient or by the attending physician and a family member or surrogate (particularly in an intensive care unit), a routine opportunity for DCD should be available to honor the deceased donor's wishes in every donor service area (DSA) of the United States.  相似文献   
8.
9.
Many polycyclic aromatic hydrocarbons containing peripherallyfused cyclopenta rings are believed to be activated primarilyby epoxidation of the cyclopenta ring. The cyclopenta epoxidesof a series of four cyclopenta benzanthracene derivatives, benz[e]aceanthrylene-5,6-oxide,benz[j]ace-anthrylene-1,2-oxide, benz(l)anthrylene-1,2-oxideand benz[k]acephenaceanthrylene-4,5-oxide were synthesized fromtheir parent hydrocarbons by formation of the bromohydrin followedby dehydrobromination, and characterized by u.v. – vis,and 1H n.m.r. spectroscopy and mass spectrometry. The mutagenicityof these compounds was investigated in the Ames plate incorporationassay with Salmonella typhimurium strain TA98. All the oxideswere active without exogenous metabolic activation (170–320His+ revertants per nanomole) and also toxic above 0.5 µg/plate.Addition of S9 protein did not increase, and generally decreased,the mutagenicity of the oxides, while toxicity was largely unchanged.These results are consistent with the postulated role of cyclopentaoxides as major contributors to the mutagenicity of the parentcompounds in the Ames assay.  相似文献   
10.
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