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   710篇
  免费   31篇
  国内免费   22篇
耳鼻咽喉   3篇
儿科学   38篇
妇产科学   1篇
基础医学   67篇
口腔科学   12篇
临床医学   85篇
内科学   112篇
皮肤病学   3篇
神经病学   45篇
特种医学   185篇
外科学   34篇
综合类   7篇
预防医学   43篇
眼科学   47篇
药学   51篇
肿瘤学   30篇
  2021年   9篇
  2019年   4篇
  2018年   6篇
  2017年   2篇
  2015年   5篇
  2014年   8篇
  2013年   25篇
  2012年   10篇
  2011年   18篇
  2010年   19篇
  2009年   16篇
  2008年   15篇
  2007年   35篇
  2006年   15篇
  2005年   27篇
  2004年   19篇
  2003年   19篇
  2002年   16篇
  2001年   18篇
  2000年   13篇
  1999年   11篇
  1998年   33篇
  1997年   46篇
  1996年   25篇
  1995年   28篇
  1994年   19篇
  1993年   13篇
  1992年   7篇
  1991年   10篇
  1990年   13篇
  1989年   21篇
  1988年   28篇
  1987年   19篇
  1986年   25篇
  1985年   30篇
  1984年   17篇
  1983年   10篇
  1982年   18篇
  1981年   8篇
  1980年   16篇
  1979年   7篇
  1978年   11篇
  1977年   11篇
  1976年   18篇
  1975年   6篇
  1974年   2篇
  1973年   3篇
  1969年   2篇
  1967年   2篇
  1965年   2篇
排序方式: 共有763条查询结果,搜索用时 31 毫秒
1.
2.
With their unique perspectives in the identification, design, promotion, and evaluation of cancer patient education programs and services, the National Cancer Institute and the American Cancer Society have the abilities to meet a wide variety of cancer patient education needs. With federal support and connections to national organizations and the comprehensive and clinical cancer center networks, the National Cancer Institute has access to nationwide experts in medical care and the resources to develop, design, and promote quality, state-of-the-art education programs. The American Cancer Society, with its strong volunteer community base, can pull together local expertise and collaborate with local organizations to meet the special needs of local population groups. In addition, the American Cancer Society volunteer committees have the flexibility to individualize programming and resources to answer specific patient/family education problems. As the number of people affected by cancer continues to raise, and as organizations realize the need to maximize their resources with collaborative efforts, the National Cancer Institute and the American Cancer Society are challenged to focus their energies on the patient education initiatives that build upon and combine their unique strengths.  相似文献   
3.
4.
5.
Summary— In the present study we have compared the steady state biopharmaceutic characteristics of four diltiazem once daily controlled release capsules: Mono-Tildiem LP 300® (300 mg), Adizem® XL (300 mg)1, Cardizem® (300 mg) and Dilacor® (240 mg). Sixteen healthy male volunteers (aged 22.9 ± 3.3 years, range 19–31 years) completed an open label, multiple oral dose, randomized, four-period crossover study without a washout period in between. The volunteers received each diltiazem formulation once daily for four days. Trough diltiazem and metabolites plasma concentrations were determined on days 3 and 4. The 24-h plasma concentration-time profiles were assessed after the dose on day 4 of each period. The following steady state pharmacokinetic parameters for diltiazem were calculated: the minimum plasma concentration (cmin), the maximum plasma concentration (cmax), the time to reach that concentration (tmax), the time interval during which the plasma concentration exceeds 50% of cmax (t50), the area under the plasma concentration-time curve (AUC72–96) and the peak-to-trough fluctuation (PTF). For the metabolites of diltiazem, N-mono-desmethyl-diltiazem (NDM) and desacetyldiltiazem (DAD), AUC72–96 (AUCNDM and AUCDAD) and the ratio metabolite/parent compound were calculated. Steady state was achieved on day 3. Except one, all controlled release formulations have satisfactory controlled release properties allowing once daily administration. However, significant (P < 0.05) differences were found between the pharmacokinetic characteristics which do not allow exchange of the various formulations. Concentrations well below 50 ng·mL-1 in the morning hours were observed for Dilacor® (240 mg) and Adizem® XL (300 mg), which could be a disadvantage of these formulations as it is well-known that ischaemic events occur at a higher rate during that part of the day. The plasma concentration profiles of NDM and DAD, the major circulating metabolites, parallel the plasma concentration profiles for the parent compound. From a clinical point of view, all treatments were well tolerated.  相似文献   
6.
PURPOSE: Adenosine receptors modulate several ocular responses; however, our understanding of factors that influence ocular extracellular adenosine levels is limited. The objective of this study was to evaluate how changes in intraocular pressure (IOP) influence endogenous levels of the purines adenosine and inosine, in the aqueous humor of normal and ocular-hypertensive patients. PATIENTS AND METHODS: Informed consent was obtained from 51 individuals undergoing cataract extraction or glaucoma surgical procedures. IOP was measured immediately prior to surgery. At the start of the surgical procedure, an aqueous sample of 75-100 microL was obtained. Purine levels were determined by reverse-phase HPLC. RESULTS: In normotensive individuals, mean aqueous adenosine and inosine levels were 5.2 +/- 1.1 and 19.4 +/- 2.2 ng/100 microL, respectively. No significant correlation between IOP and purine concentration was measured in this group. In ocular hypertensive individuals, the mean aqueous adenosine and inosine concentration was significantly elevated when compared to normotensive individuals. In the ocular hypertensive individual, this elevation in adenosine level was significantly correlated with IOP (r(2) = 0.42). CONCLUSIONS: These results demonstrate that in ocular hypertensive individuals, aqueous adenosine concentration is correlated with IOP. As the activation of adenosine receptors can modulate IOP and retinal blood flow, adenosine release during periods of ocular hypertension may play an important role in the physiological responses to elevated IOP.  相似文献   
7.
Intestinal obstruction proximal to a transition zone without an interposed physical barrier usually indicates Hirschsprung disease. The authors report one case of focal small bowel muscular thinning just distal to a transition zone that produced clinical and radiographic findings that simulated long-segment Hirschsprung disease in a 2-day-old infant.  相似文献   
8.
Recently, in-vitro maturation (IVM) of immature human oocytes recovered from non-stimulated follicles has been applied in the treatment of infertility. However, in previous reports, very few embryos cultured in conventional medium have reached the expanded blastocyst stage following in-vitro maturation and fertilization (IVM/IVF). The objective of this study was to investigate whether the developmental competence of human embryos following IVM/IVF could be enhanced by the use of a human ampullary cell co-culture system. Immature human oocytes were aspirated from small follicles at Caesarean section and then cultured in medium containing human menopausal gonadotrophin for 36 to 48 h, followed by insemination. Zygotes were randomly cultured either in conventional culture medium alone or in the co-culture system. Of 48 embryos cultured in conventional medium alone, all arrested at the 2-16- cell stage on day 3 after insemination. Of 46 embryos cultured in the co-culture system, 26 embryos (56.5%) arrested at the 2-16-cell stage. Six embryos (13%) developed to the morula stage. Fourteen embryos (30.4%) developed to expanded blastocysts and two blastocysts were hatching on day 7 after insemination. We conclude that co-culture significantly enhances the development of blastocysts in embryos resulting from IVM/IVF.   相似文献   
9.
The differentiation of the urinogenital system and the appendicular skeleton in vertebrates is under the control of Hox genes. The common control of digit and gonad differentiation raises the possibility that patterns of digit formation may relate to spermatogenesis and hormonal concentrations. This work was concerned with the ratio between the length of the 2nd and 4th digit (2D:4D) in humans. We showed that (i) 2D:4D in right and left hands has a sexually dimorphic pattern; in males mean 2D:4D = 0.98, i.e. the 4th digit tended to be longer than the 2nd and in females mean 2D:4D = 1.00, i.e. the 2nd and 4th digits tended to be of equal length. The dimorphism is present from at least age 2 years and 2D:4D is probably established in utero; (ii) high 2D:4D ratio in right hands was associated with germ cell failure in men (P = 0.04); (iii) sperm number was negatively related to 2D:4D in the right hand (P = 0.004); (iv) in men testosterone concentrations were negatively related to right hand 2D:4D and in women and men LH (right hand), oestrogen (right and left hands) and prolactin (right hand) concentrations were positively correlated with 2D:4D ratio and (v) 2D:4D ratio in right hands remained positively related to luteinizing hormone and oestrogen after controlling for sex, age, height and weight.   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