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   19773篇
  免费   1073篇
  国内免费   68篇
耳鼻咽喉   239篇
儿科学   505篇
妇产科学   365篇
基础医学   2832篇
口腔科学   415篇
临床医学   1756篇
内科学   3662篇
皮肤病学   812篇
神经病学   2287篇
特种医学   1144篇
外国民族医学   11篇
外科学   2993篇
综合类   156篇
一般理论   5篇
预防医学   980篇
眼科学   314篇
药学   1061篇
中国医学   64篇
肿瘤学   1313篇
  2023年   158篇
  2022年   252篇
  2021年   476篇
  2020年   314篇
  2019年   448篇
  2018年   485篇
  2017年   441篇
  2016年   539篇
  2015年   566篇
  2014年   748篇
  2013年   910篇
  2012年   1442篇
  2011年   1503篇
  2010年   889篇
  2009年   765篇
  2008年   1274篇
  2007年   1260篇
  2006年   1205篇
  2005年   1196篇
  2004年   1021篇
  2003年   951篇
  2002年   890篇
  2001年   215篇
  2000年   205篇
  1999年   240篇
  1998年   211篇
  1997年   150篇
  1996年   156篇
  1995年   104篇
  1994年   105篇
  1993年   82篇
  1992年   100篇
  1991年   111篇
  1990年   73篇
  1989年   73篇
  1988年   71篇
  1987年   79篇
  1986年   70篇
  1985年   68篇
  1984年   60篇
  1983年   48篇
  1982年   47篇
  1981年   45篇
  1980年   48篇
  1979年   58篇
  1978年   47篇
  1977年   40篇
  1976年   32篇
  1973年   27篇
  1972年   26篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
52.
Summary Two patients are described with the triad of tonic pupil, hyporeflexia and segmental anhidrosis (Ross syndrome). Only 18 cases of this syndrome have been reported in the literature so far. While tonic pupil and reduced sweating can be attributed to the affection of postganglionic cholinergic parasympathetic and sympathetic fibres projecting to the iris and sweat glands, respectively, the pathogenesis of diminished or lost tendon jerks remains obscure. To identify the characteristic clinical features, the previous cases of Ross syndrome are reviewed. Recent evidence of subclinical disturbances of sweating in most patients with Adie's syndrome, i.e. tonic pupil and areflexia, casts doubt on the nosological concept of Ross syndrome as a distinct clinical entity.  相似文献   
53.
The aim of this study was to compare the efficacy and safety of a monomethoxypolyethylene glycol (mPEG) modified grass pollen mix allergen preparation (mPEG-gm) and a partly purified grass pollen mix allergen preparation (gm) in hyposensitization (HS), evaluating both products at two dose levels. Thirty adult patients with allergic rhinoconjunctivitis were allocated into two treatment groups based on their sensitivity to conjunctival provocation tests (CPT). Treatment was given in a double-blind manner. The starting dose was 20 BU and was approximately doubled weekly up to 20,000 BU the first year and 120,000 BU the second year. Skin testing and CPT were performed before treatment and at each dose level. All patients reached 20,000 BU the first year. Twenty-five patients continued the second year. Twenty-one of those reached 120,000 BU (9/12 on mPEG-gm and 12/13 on gm). The frequency of general side effects was reduced by about 50% with the mPEG grass mix compared with native grass mix. A significant improvement in the conjunctival sensitivity was found in both treatment groups the second year (120,000 BU) but not the first year (20,000 BU). Seventy-eight percent of the patients in the gm group and 50% in the mPEG-gm group improved by CPT (not statistically significant). The skin sensitivity was reduced after 1 year at low dose in 69% of the gm-treated patients and 33% of the mPEG treated patients. After the second year at high dose levels, the skin sensitivity decreased in all patients.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
54.
Supraventricular tachyarrhythmias frequently complicate myocardial revascularization. Intravenous administration of verapamil has been effective in terminating these arrhythmias. To determine the effects of verapamil on left ventricular systolic function, we implanted ultrasonic dimension transducers in dogs and, after they had recovered from the operation, studied them while they were awake and unsedated. Intravenous administration of verapamil (0.2 mg/kg) resulted in an elevation of cardiac output above baseline because of reflex-induced tachycardia. Contractility, as measured by the load-independent end-systolic pressure-volume relationship, remained unchanged. When the animals were pretreated with atropine and propranolol, verapamil resulted in a fall in cardiac output and contractility. The intact animal responded to the vasodilatory effect of verapamil by releasing catecholamines to maintain cardiac output and hemodynamic stability. Only when this compensatory mechanism was blocked by a beta-adrenergic blocker do the inherently negative inotropic and chronotropic effects of verapamil become apparent. The clinical ramifications of this finding are of greater importance to the surgeon as more patients receive beta-adrenergic blocking agents up to the time of the immediate preoperative period. We conclude that verapamil should be administered with caution to patients with supraventricular tachyarrhythmias who have been receiving beta-adrenergic blocking agents.  相似文献   
55.
We report on the hypothalamic-pituitary-gonadal function in 2 male infants with the Smith-Lemli-Opitz (SLO or RSH) syndrome. Both infants had abnormal external genitalia. Basal and LHRH stimulated plasma gonadotropins were normal for age (1 month). Plasma testosterone, androstenedione, and dehydroepiandrosterone sulfate were normal for age and sex. Some forms of congenital adrenal hyperplasia (17,20-desmolase deficiency, 17α-hydroxylase deficiency, and 3β-hydroxysteroid dehydrogenase deficiency) were ruled out by hormonal studies. The endocrinological findings indicate a normal hypothalamic-pituitary-gonadal function and a normal adrenal steroid biosynthesis in these 2 patients. A partial androgen receptor defect causing the genital malformations seems possible in one patient. Whether 5α-reductase deficiency is the cause of the male pseudohermaphroditism in SLO syndrome remains the subject of future studies. © 1992 Wiley-Liss, Inc.  相似文献   
56.
Limited efficacy of chemotherapy in most solid tumors has revived interest in immunotherapeutic approaches for cancer. One novel form of immunotherapy is the use of cancer vaccines consisting of tumor cells genetically engineered to secrete cytokines. The rationale for this immunization strategy is based on the existence of tumor-specific antigens, on the importance of the cellular arm of the immune system in mediating an effective antitumor response, and on the role of cytokines in regulating the cellular immune response. Such tumor vaccines showed considerable promise in various animal models and induced potent antitumor immunity in the host, which led to regression of established tumors and, moreover, produced immunological memory protecting animals from a subsequent tumor challenge at a distant site. Translated to the human patient, this implies that genetically modified tumor vaccines may be able to eradicate or reduce existing tumor deposits to subclinical levels as well as provide long-term protection from regrowth of tumor cells. This report will review and discuss the concept and rationale for the use of cytokine-secreting tumor vaccines for the treatment of human malignancies.  相似文献   
57.
Insulin-like growth factor 1 (IGF-1) is a potent mitogen for human breast-cancer cells in vitro. In circulation, most of IGF-1 is bound to IGF-binding protein 3 (IGFBP-3). This high-affinity binding is thought to have an important limiting effect on the availability of IGF-1 for biological activity. To assess the availability of IGF-1 for receptor binding, we determined serum levels of IGF-1 and IGFBP-3 and IGF-1/IGFBP-3 ratios. In a case-control study, 150 women aged 38 to 75 years presenting with stage-l or-II breast cancer were investigated just prior to surgery (n = 76), or to irradiation one month after surgery (n = 74). The population-based control group consisted of 441 women of the same age having no breast cancer. Women reporting diabetes mellitus or other hormonal abnormalities were excluded. Premenopausal cases showed elevated IGF-1 serum concentrations, decreased IGFBP-3 levels and increased IGF-1/IGFBP-3 ratios. The IGF-1/IGFBP-3 ratio was a significant breast-cancer risk factor, also after adjustment for age, family history, height, body-mass index, body-fat distribution, and serum levels of C-peptide. The relative risk was 7.34 for the highest compared with the lowest quintile of IGF-1/IGFBP-3. The presence or absence of tumor had no influence on these results. Increased levels of available IGF-1 in the circulation of pre-menopausal women may contribute to the development of breast cancer. © 1995 Wiley-Liss Inc.  相似文献   
58.
59.
This study compares health status, demographic and socioeconomic characteristics of users and non-users of NHS Direct in order to establish whether the service is being used by people with the greatest need for healthcare services. It suggests that use of NHS Direct is widespread among carers of children under 5 years old, but there is evidence that it may not be accessed equitably by those from ethnic minorities, lower socioeconomic groups and those with established ill health.  相似文献   
60.
OBJECTIVE: Apathy is among the most frequent neuropsychiatric symptoms in dementia, particularly Alzheimer disease. The Apathy Evaluation Scale (AES) has been widely employed for assessing apathy in different patient groups. To further facilitate the usage of the AES, an abbreviated version was constructed. METHOD: On basis of a sample of 356 nursing home residents, a cross-validation procedure was carried out to develop a brief version of the AES. According to a thorough clinical examination, 85% of the residents were demented, 8% presented with mild cognitive impairment, whereas 7% did not present any cognitive deficits. After subdividing the patient group into two matched samples, the first subsample was used to identify problematic items due to defined psychometric and content-related criteria. The original 18-item scale was thus reduced to 10 items. Psychometric properties of the shortened version were subsequently reassessed in the second subsample. RESULTS: The short version demonstrated favorable psychometric properties that could be confirmed by cross-validation with the second sample. Correlations with the original full-length version were high (r = 0.97 for both subsamples); the shortened scale yielded no substantial losses regarding internal consistency or construct validity (correlations with the respective subscales of the Neuropsychiatric Inventory). CONCLUSION: The frequency of apathetic symptoms in the nursing home residents included confirms the clinical importance of apathy for understanding dementia. Given this specific patient population, setting, and mode of data collection, the short-version AES seems to be a valuable and time-efficient instrument for assessing apathy.  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