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   8594篇
  免费   613篇
  国内免费   113篇
耳鼻咽喉   105篇
儿科学   296篇
妇产科学   291篇
基础医学   931篇
口腔科学   160篇
临床医学   942篇
内科学   1854篇
皮肤病学   216篇
神经病学   860篇
特种医学   228篇
外科学   1403篇
综合类   175篇
一般理论   3篇
预防医学   419篇
眼科学   135篇
药学   656篇
中国医学   70篇
肿瘤学   576篇
  2023年   35篇
  2022年   76篇
  2021年   219篇
  2020年   105篇
  2019年   196篇
  2018年   234篇
  2017年   166篇
  2016年   186篇
  2015年   253篇
  2014年   316篇
  2013年   435篇
  2012年   560篇
  2011年   625篇
  2010年   376篇
  2009年   355篇
  2008年   519篇
  2007年   521篇
  2006年   524篇
  2005年   465篇
  2004年   446篇
  2003年   326篇
  2002年   312篇
  2001年   276篇
  2000年   219篇
  1999年   217篇
  1998年   62篇
  1997年   63篇
  1996年   58篇
  1995年   33篇
  1994年   46篇
  1993年   44篇
  1992年   104篇
  1991年   102篇
  1990年   105篇
  1989年   98篇
  1988年   80篇
  1987年   71篇
  1986年   58篇
  1985年   56篇
  1984年   54篇
  1983年   37篇
  1982年   16篇
  1981年   25篇
  1980年   20篇
  1979年   41篇
  1978年   23篇
  1977年   20篇
  1976年   23篇
  1975年   19篇
  1974年   23篇
排序方式: 共有9320条查询结果,搜索用时 656 毫秒
91.
BACKGROUND/AIM: A mechanism suggested to cause injury to preserved organs is the generation of oxygen free radicals. Lipid peroxidation is one of the biological damages caused by oxygen free radicals. It is our aim to investigate whether magnolol, a strong antioxidant, suppresses the generation of oxygen free radicals and improves the viability of cold-preserved warm-reperfused rat livers. MATERIALS AND METHODS: In vitro lipid peroxidation was induced in rat hepatic mitochondria with ADP and FeSO4. The inhibitory effect of magnolol on lipid peroxidation was measured with oxygen consumption and malondialdehyde (MDA) formation. Subsequently, we preserved and reperfused rat livers in preservation solutions that contained magnolol. The hepatic enzymes and liver MDA were measured to assess the protective effect of magnolol on isolated rat livers. RESULTS: In rat hepatic mitochondria, magnolol was 470 times more potent than alpha-tocopherol in inhibiting oxygen consumption and 340 times more potent than alpha-tocopherol in inhibiting MDA formation. Addition of magnolol to Ringer's lactate solution had a protective effect, in terms of MDA formation and leakage of hepatic enzymes, on warm-reperfused but not cold-stored liver tissue. Addition of magnolol to University of Wisconsin (UW) solution, a widely used preservation solution, did not modify the effect of this solution on isolated liver tissues. CONCLUSIONS: We conclude that magnolol is an effective antioxidant and suppresses lipid peroxidation in rat liver mitochondria and can be used as a rinsing solution in protecting transplanted organs from lipid peroxidation during reperfusion, especially for those organs not preserved with UW solution.  相似文献   
92.
OBJECTIVES: The aim of this study is to evaluate the efficacy and tolerability of sertraline in patients with major depression who have failed to respond to an adequate trial of moclobemide. METHOD: Sixty-three patients with major depression who had discontinued moclobemide within the last 6 weeks due to lack of efficacy were recruited from multiple psychiatric services in Victoria and Queensland. After a wash-out period, patients were treated with sertraline 50 mg once daily for 4 weeks. If there was an insufficient response, the dose was titrated upwards to a maximum of 200 mg/day, with 2 weeks at each dosage level. By the end of the study, patients had received a fixed dose of sertraline for 8 weeks. The main outcome measures were the 17-item Hamilton Rating Scale for Depression (HAMD) and Clinical Global Impression (CGI) scales. Secondary outcome measures included the Montgomery-Asberg Depression Rating Scale (MADRS) and Beck Depression Inventory (BDI). RESULTS: Of the 62 intention-to-treat patients enrolled, 48 (77%) responded to sertraline (i.e. experienced > or =50% reduction in HAMD total score from baseline and had a final HAMD score of < or =17). Fifty-four (87%) patients were at least 'minimally improved' on the CGI scale. There were also significant improvements in mean total MADRS and BDI scores. Sertraline was well tolerated. Adverse events were reported by 84% of patients, but only 5% withdrew due to adverse events. CONCLUSIONS: This study shows that patients with major depression who have failed to respond to moclobemide can generally be treated successfully with sertraline.  相似文献   
93.
94.
We investigated the association between schizophrenic psychosis and an intronic polymorphism of the presenilin-1 (PS1) gene in a Chinese population. Schizophrenic and control groups had similar PS1 genotype distributions and allele frequencies, indicating that this polymorphism may not be involved in the development of schizophrenia.  相似文献   
95.
A splint has been designed to correct the congenital clasped thumb. It is like a short opponens splint that can keep the thumb in a position of abduction and extension without limiting wrist movement. The application of the splint was easy and adjustment for fit could be made at each visit if necessary. The device has been used in 11 infant patients (17 thumbs) with congenital clasped thumb of the supple type. The functional results were excellent in 15 of 17 thumbs, and the other two were good according to the grading system of Weckesser et al. (1968).  相似文献   
96.
Chiu DT 《Hand Clinics》1999,15(4):667-71, ix
Autogenous venous nerve conduit (AVNC) has evolved from an experimental idea to a clinical reality over the last two decades. The effectiveness of AVNC for reconstruction of a peripheral nerve with a nerve gap of less than 3 cm has been established and confirmed. An exciting application of this technique in the near future is to use the conduit as a vehicle for moderation and modulation of the cellular and molecular ambience for nerve regeneration.  相似文献   
97.
Studies of minority ethnic women and cancer screening have, in the past, suffered from many theoretical and methodological weaknesses. In addition, no attempts have been made to study the complexity of the issue involved in the intercultural context, or the possible contribution of women's experiences to low uptake rates. In order to further our understanding of the issues, an alternative approach, participatory action research (PAR), was adopted to identify factors that might have contributed to the persistently low participation of minority ethnic women in the cervical screening programme, and address them collaboratively. This paper presents the key findings of the ‘problem identification' phase of the project. Using mainly the focus-group method, it explores both smear takers' and minority ethnic women's perceptions and experiences of cervical screening. Data suggest that there was a divergence in perceptions held by these groups regarding cervical screening, which contributed to negative experiences for both groups. There is also clear evidence of dysfunctional clinical communication arising from these differing perceptions. Opportunistic screening at post-natal examination adopted by many general practices appeared to have perpetuated the perceptions that the majority of minority ethnic women held about the purpose of the smear test. Compounded by language differences, the majority of women who had undergone smear testing understood neither the purpose of screening programme nor the procedure of the test. This has clear implications for promoting regular uptake, and more importantly for informed consent and choice.  相似文献   
98.
Dihydropyrimidinones such as compound 12 exhibited high binding affinity and subtype selectivity for the cloned human alpha(1a) receptor. Systematic modifications of 12 led to identification of highly potent and subtype-selective compounds such as (+)-30 and (+)-103, with high binding affinity (K(i) = 0.2 nM) for alpha(1a) receptor and greater than 1500-fold selectivity over alpha(1b) and alpha(1d) adrenoceptors. The compounds were found to be functional antagonists in human, rat, and dog prostate tissues. Compound (+)-103 exhibited excellent selectively to inhibit intraurethral pressure (IUP) as compared to lowering diastolic blood pressure (DBP) in mongrel dogs (K(b)(DBP)/K(b)(IUP) = 40) suggesting uroselectivity for alpha(1a)-selective compounds.  相似文献   
99.
Acute catatonic syndromes occurring in the context of various medical and neuropsychiatric conditions, including schizophrenia, have been shown to respond well to benzodiazepines (BZD). However, there have been no studies specifically designed to address the BZD treatment response of persistent catatonic states. Eighteen patients with clinically stable chronic schizophrenia, who also displayed enduring catatonic features, underwent a 12-week long, random assignment, double-blind, placebo-controlled cross-over trial with lorazepam (6 mg/day). A comprehensive assessment, including the subjects’ clinical and motor (catatonic as well as drug-induced movement disorders) condition, was performed at baseline and four weekly intervals thereafter. Pre-existing medication was kept constant throughout the study. Lorazepam had no effect on the subjects’catatonic signs and symptoms, suggesting that acute and chronic catatonic syndromes associated with schizophrenic illness might have a different neurobiological basis. Received: 25 May 1998/Final version: 22 September 1998  相似文献   
100.
An N-ras-related transforming gene was detected in the human lung carcinoma cell line SW-1271 and molecularly cloned. The lesion responsible for its acquisition of transforming activity was localized to a single nucleotide transition from A to G in codon 61 of the predicted protein. This lesion in the second exon results in the substitution of arginine for glutamine at this position. These findings, together with previous studies, indicate that the activation of ras oncogenes in human tumors is most commonly due to point mutations at one of two major "hot spots" in the ras coding sequence.  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