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   10062篇
  免费   686篇
  国内免费   32篇
耳鼻咽喉   70篇
儿科学   357篇
妇产科学   184篇
基础医学   1450篇
口腔科学   217篇
临床医学   1574篇
内科学   1840篇
皮肤病学   141篇
神经病学   1014篇
特种医学   166篇
外科学   870篇
综合类   98篇
一般理论   19篇
预防医学   1348篇
眼科学   108篇
药学   697篇
中国医学   35篇
肿瘤学   592篇
  2023年   76篇
  2022年   107篇
  2021年   211篇
  2020年   149篇
  2019年   209篇
  2018年   263篇
  2017年   198篇
  2016年   197篇
  2015年   232篇
  2014年   338篇
  2013年   517篇
  2012年   663篇
  2011年   804篇
  2010年   468篇
  2009年   369篇
  2008年   724篇
  2007年   710篇
  2006年   715篇
  2005年   676篇
  2004年   633篇
  2003年   530篇
  2002年   532篇
  2001年   88篇
  2000年   65篇
  1999年   94篇
  1998年   131篇
  1997年   82篇
  1996年   82篇
  1995年   67篇
  1994年   66篇
  1993年   65篇
  1992年   59篇
  1991年   47篇
  1990年   44篇
  1989年   48篇
  1988年   30篇
  1987年   30篇
  1986年   20篇
  1985年   33篇
  1984年   28篇
  1983年   30篇
  1982年   41篇
  1981年   45篇
  1980年   35篇
  1979年   27篇
  1978年   36篇
  1977年   18篇
  1975年   16篇
  1973年   12篇
  1972年   10篇
排序方式: 共有10000条查询结果,搜索用时 11 毫秒
81.
Equity theory has recently been found to be a useful framework for under-standing the effects of imbalances in intimate contractual relationships such as marriage. Equitable couples seem to be happier, more satisfied with their relationship, and more confident that it will last than are their more mismatched, i.e., inequitable, counterparts. Furthermore, inequitable couples predictably act to set things right in their marriage. They either restore actual equity to the relationship or psychologically set their relationship in balance. If neither works, they may leave the field. Extramarital sex may be viewed as an equity restoration mechanism in that (1) it may be used by the deprived partner to achieve actual equity, (2) it may indicate a partner's readiness to leave the relationship because he feels he can do better, or (3) it may represent a desire to achieve equity in an alternative relationship(s) when inequity pervades the primary one. The hypothesis that the inequitable/underbenefited group should be more likely than the equitable group or the inequitable/overbenefited group to have engaged in extramarital sex was tested using data from a large-scale Psychology Todayquestionnaire. The results indicated that men and women in inequitable/under-benefited relationships had more extramarital affairs and began their extramarital activities earlier than did men and women in equitable and inequitable/over-benefited relationships. Alternative explanations of this finding, sex-role demands and length of the relationship, are explored and discarded as untenable. Research supported in part by National Institute of Mental Health Grant MH 26681.  相似文献   
82.
Gallium 67 imaging was used in 12 patients with documented Hansen's disease undergoing treatment or not, in an attempt to determine the pattern of the disease. Diagnosis was confirmed by histopathology in all patients. The Mitsuda reaction was seen in all patients. Specific nuclear studies were performed when needed to evaluate particular organs better. Gallium 67 images show homogeneous, diffuse and moderate accumulation over the entire skin surface (except for the face) of untreated patients with multibacillary disease. The facial skin in these cases presented homogeneous, diffuse but very marked uptake of gallium. Internal organ involvement was variable. There was a very good correlation among clinical, scintigraphic, immunological and histopathological data. The pattern of the body skin (skin outlining) and facial skin (beard distribution) may be distinct for untreated patients with multibacillary leprosy.  相似文献   
83.
Rats were trained to discriminate the stimulus properties of l-5-hydroxytryptophan (l-5-HTP) (30 mg/kg SC), the immediate precursor of serotonin (5-HT). The peripheral decarboxylase inhibitor R04-4602, administered prior to l-5-HTP, greatly attenuated the disruptive effects observed on responding when l-5-HTP alone was injected. Following acquisition, the discrimination was dosedependent and generalized to fenfluramine, a 5-HT-releasing drug, but not to amphetamine, a catecholamine-releasing agent. Further evidence for the involvement of 5-HT receptor stimulation in mediating the discrimination was that pretreatment with fluoxetine, a highly specific 5-HT uptake inhibitor, markedly potentiated the cue. Nevertheless, the classical 5-HT antagonists methysergide, cyproheptadine, metergoline, and methiothepin did not block the l-5-HTP-related discriminative stimulus. This finding suggested that the cue properties of l-5-HTP might be mediated by a population of 5-HT receptors previously identified electrophysiologically in limbic structures. As in the present experiment, the putative 5-HT antagonists did not block the synaptic effects of 5-HT in these structures.  相似文献   
84.
PURPOSE: Monoclonal antibody-mediated targeting of liposomal anticancer drugs to surface antigens expressed on malignant B cells can be an effective strategy for treating B-cell malignancies. In a murine model of human B-cell lymphoma, we have made in vitro and in vivo comparisons of long-circulating sterically stabilized (Stealth) immunoliposome (SIL) formulations of two anticancer drugs, vincristine (VCR) and doxorubicin (DXR), with different mechanisms of action and drug release rates. EXPERIMENTAL DESIGN: SIL formulations of VCR or DXR were conjugated to the monoclonal antibody anti-CD19 (SIL[alphaCD19]) or its Fab' fragments (SIL[Fab']). Specific binding of SILs to Namalwa cells was studied using radiolabeled liposomes, and cytotoxicities of DXR- or VCR-loaded SILs were quantitated by a tetrazolium assay. Pharmacokinetic and drug leakage experiments were performed in mice using dual-labeled liposomes, and the therapeutic responses of SILs were evaluated in a Namalwa (human B lymphoma) cell xenograft model. RESULTS: SIL[alphaCD19] or SIL[Fab'] had higher association with and cytotoxicity against Namalwa cells than nontargeted liposomes. SIL[Fab'] had longer circulation times than SIL[alphaCD19], and VCR had faster release rates from the liposomes than DXR. SIL formulations of either VCR or DXR had significantly better therapeutic outcomes than nontargeted liposomes or free drugs. SILs loaded with VCR were superior to those loaded with DXR. SIL[Fab'] had better therapeutic outcomes than SIL[alphaCD19] for the drug DXR but were equally efficacious for the drug VCR. CONCLUSIONS: Treatment of a B lymphoma model with single injections of anti-CD19-targeted liposomal formulations of VCR resulted in high levels of response and long-term survivors. Responses to anti-CD19-targeted liposomal DXR were more modest, although the longer circulation times of SIL[Fab'] versus SIL[alphaCD19] led to superior therapeutics for DXR-loaded immunoliposomes.  相似文献   
85.
PURPOSE: The idiotype (Id) of the immunoglobulin on a given B-cell malignancy is a clonal marker that can serve as a tumor-specific antigen. We developed a novel vaccine formulation by incorporating Id protein with liposomal lymphokine that was more potent than a prototype, carrier-conjugated Id protein vaccine in preclinical studies. In the present study, we evaluated the safety and immunogenicity of this vaccine in follicular lymphoma patients. EXPERIMENTAL DESIGN: Ten patients with advanced-stage follicular lymphoma were treated with five doses of this second generation vaccine after chemotherapy-induced clinical remission. All patients were evaluated for cellular and humoral immune responses. RESULTS: Autologous tumor and Id-specific type I cytokine responses were induced by vaccination in 10 and 9 patients, respectively. Antitumor immune responses were mediated by both CD4+ and CD8+ T cells, were human lymphocyte antigen class I and II associated, and persisted 18 months beyond the completion of vaccination. Specific anti-Id antibody responses were detected in four patients. After a median follow-up of 50 months, 6 of the 10 patients remain in continuous first complete remission. CONCLUSIONS: This first clinical report of a liposomal cancer vaccine demonstrates that liposomal delivery is safe, induces sustained tumor-specific CD4+ and CD8+ T-cell responses in lymphoma patients, and may serve as a model for vaccine development against other human cancers and infectious pathogens.  相似文献   
86.
PURPOSE: This article describes baseline data collection and the intervention design of Partnership for Health, a smoking cessation intervention for smokers in the Childhood Cancer Survivors Study. The purpose of this article is to evaluate demographic, psychosocial, and cancer-related factors that are associated with smoking behavior and mediators of smoking cessation. PATIENTS AND METHODS: This study includes 796 smokers from the Childhood Cancer Survivors Study database who were diagnosed with cancer before the age of 21, had survived at least 5 years, and were at least 18 years of age at the time of the baseline survey. Correlates of smoking behaviors included smoking rate, number of recent quit attempts, and nicotine dependence; two key mediators of smoking cessation, readiness to quit smoking and self-efficacy, were also assessed. RESULTS: Participants smoked, on average, 14 cigarettes/day; 53.2% were nicotine dependent, and 58% had made at least one quit attempt in the past year. Smoking behaviors were primarily associated with demographic variables; mediators of cessation were primarily associated with age at cancer diagnosis and perceived vulnerability to smoking-related illnesses. Severity of psychologic symptoms was associated with increased smoking rate, high nicotine dependence, and low self-efficacy. Support for quitting was related to smoking rate, number of quit attempts, readiness to quit smoking, and self-efficacy. CONCLUSION: These findings indicate that many cancer survivors who smoke are receptive to smoking cessation interventions. Factors related to mediators of smoking cessation might be particularly good targets for intervention.  相似文献   
87.
88.
Genetic polymorphism in HPC2/ELAC2 was recently associated with risk of sporadic prostate cancer. To determine the contribution of two HPC2/ELAC2 missense variants (Ser217Leu and Ala541Thr) to the risk of developing prostate cancer, we conducted a population-based case-control study of middle-aged men (40-64 years). Cases (n=591) were ascertained from the Seattle-Puget Sound Surveillance, Epidemiology, and End Results Cancer Registry and Controls (n=538) from the same general population were identified through random-digit dialing. Subjects were residents of King County, Washington, and were frequency matched on age. Cases (32%) had a slightly higher frequency of the Leu217 variant compared with controls (29%), but there were no differences in the frequency of the Thr541 allele (4%). When considering joint genotypes, white men homozygous for the Leu217 variant on an Ala541/Ala541 background had an increased risk of prostate cancer [odds ratio (OR)=1.84; 95% confidence interval (CI), 1.11-3.06]. Different risk profiles were also observed when cases were stratified by disease aggressiveness. Men with at least one Leu217 allele had an elevated risk (OR=1.34; 95% CI, 1.02-1.76) of less aggressive prostate cancer (localized stage and Gleason score < or = 7), with a stronger association among men with two Leu217 alleles (OR=1.73; 95% CI, 1.08-2.77). The Ala541Thr polymorphism was not associated with risk, and neither variant was associated with more aggressive prostate cancer phenotypes. We estimate that the Ser217Leu genotype may account for approximately 14% of less aggressive prostate cancer cases and 9% of all sporadic cases in the general United States population of white men 相似文献   
89.
Urogenital ageing and its effect on sexual health in older British women   总被引:4,自引:0,他引:4  
Objective To provide information on the extent of problems of urogenital ageing in older British women.
Design A MORI survey of a representative population sample of older British women.
Setting Home interviews.
Participants Two thousand and forty-five women aged 55–85+.
Results Urogenital symptoms had affected 48.8% of the women at some time, but no more than 11% were currently affected by individual symptoms; however, these were often of long duration. The majority (73%) were not sexually active, with lack of a partner being a factor for many. There was also a decreasing prevalence of sexual activity with increasing age. Those sexually active in the 65–74 year old age group (   n = 148  ) tended to have a similar sexual frequency (at least once per month) compared with the younger women studied. Approximately 12% of those who reported dyspareunia and/or vaginal dryness claimed a severe problem; 33% did not seek professional advice and 36% resorted to an over the counter remedy. Use of hormone replacement therapy was generally of relatively short duration. There was a declining gradient of ever-use with age.
Conclusions The extent of significant urogenital symptoms is relatively low, but some women are seriously affected and use self-help as well as professional assistance. The extent of sexual activity in older women and factors affecting this have been defined, and the effect of urogenital symptoms on sexual activity demonstrated.  相似文献   
90.
To update its cancer statistics, the newly established Middle East Cancer Society examined the cancer frequency patterns in Egypt and the Gaza Strip. The results revealed differing overall patterns. For men the highest frequencies were found for lymphoma, bladder cancer and cancers of the oral cavity and pharynx in Egypt, and for lung cancer, leukaemia and lymphoma in Gaza. For women, breast cancer had the highest frequency in both areas, followed by cancers of the oral cavity and pharynx in Egypt, and leukaemia and lymphoma in Gaza. The distribution of cancer occurrence by organ system also varied. In the light of the different ethnicities, lifestyles, socioeconomic levels and carcinogenic exposure among the countries of the Middle East, this kind of comparison can provide the background for more sophisticated approaches for discerning risk factors in cancer. We believe that further cooperation among participating countries will overcome the present limitations in data collection, registration and access.  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