全文获取类型
收费全文 | 4486篇 |
免费 | 482篇 |
国内免费 | 66篇 |
专业分类
耳鼻咽喉 | 100篇 |
儿科学 | 209篇 |
妇产科学 | 63篇 |
基础医学 | 616篇 |
口腔科学 | 63篇 |
临床医学 | 387篇 |
内科学 | 895篇 |
皮肤病学 | 87篇 |
神经病学 | 225篇 |
特种医学 | 389篇 |
外科学 | 859篇 |
综合类 | 137篇 |
一般理论 | 5篇 |
预防医学 | 433篇 |
眼科学 | 16篇 |
药学 | 312篇 |
中国医学 | 1篇 |
肿瘤学 | 237篇 |
出版年
2021年 | 58篇 |
2020年 | 50篇 |
2019年 | 51篇 |
2018年 | 61篇 |
2017年 | 56篇 |
2016年 | 65篇 |
2015年 | 80篇 |
2014年 | 105篇 |
2013年 | 129篇 |
2012年 | 159篇 |
2011年 | 184篇 |
2010年 | 109篇 |
2009年 | 95篇 |
2008年 | 151篇 |
2007年 | 188篇 |
2006年 | 171篇 |
2005年 | 209篇 |
2004年 | 135篇 |
2003年 | 145篇 |
2002年 | 135篇 |
2001年 | 168篇 |
2000年 | 152篇 |
1999年 | 133篇 |
1998年 | 93篇 |
1997年 | 100篇 |
1996年 | 102篇 |
1995年 | 103篇 |
1994年 | 72篇 |
1993年 | 66篇 |
1992年 | 86篇 |
1991年 | 83篇 |
1990年 | 110篇 |
1989年 | 126篇 |
1988年 | 90篇 |
1987年 | 104篇 |
1986年 | 80篇 |
1985年 | 103篇 |
1984年 | 81篇 |
1983年 | 65篇 |
1982年 | 46篇 |
1981年 | 34篇 |
1980年 | 40篇 |
1979年 | 61篇 |
1978年 | 46篇 |
1977年 | 55篇 |
1976年 | 60篇 |
1975年 | 57篇 |
1974年 | 38篇 |
1973年 | 32篇 |
1971年 | 47篇 |
排序方式: 共有5034条查询结果,搜索用时 15 毫秒
41.
Differential RNA fingerprinting as a tool in the analysis of spermatozoal gene expression 总被引:9,自引:1,他引:9
Miller David; Tang Pei-Zhong; Skinner Clare; Lilford Richard 《Human reproduction (Oxford, England)》1994,9(5):864-869
The apparent decline in human male fertility and the concomitantincrease in testicular pathology have prompted discussion ofthe underlying molecular mechanisms which may underpin theseobservations. While monitoring the expression of protamlne-2genes in the human ejaculate, we found a representative complementof sperm mRNAs following sequence-independent amplificationof reverse-transcribed cDNAs with the polymerase chain reaction(RT-PCR). The revelation of unique sperm-derived PCR productsusing this method suggests that it should now be possible toinvestigate gene expression in human spermatogenesis by differentialRNA fingerprinting of ejaculate spermatozoa. The Identificationof molecular markers and the corresponding genes associatedwith male Infertility will be considerably enhanced by theseinvestigations while obviating the requirement for invasivebiopsy. 相似文献
42.
Chaudhry SS Gazzard J Baldock C Dixon J Rock MJ Skinner GC Steel KP Kielty CM Dixon MJ 《Human molecular genetics》2001,10(8):835-843
Fibrillins are large, cysteine-rich glycoproteins that form microfibrils and play a central role in elastic fibrillogenesis. Fibrillin-1 and fibrillin-2, encoded by FBN1 on chromosome 15q21.1 and FBN2 on chromosome 5q23-q31, are highly similar proteins. The finding of mutations in FBN1 and FBN2 in the autosomal dominant microfibrillopathies Marfan syndrome (MFS) and congenital contractural arachnodactyly (CCA), respectively, has highlighted their essential role in the development and homeostasis of elastic fibres. MFS is characterized by cardiovascular, skeletal and ocular abnormalities, and CCA by long, thin, flexed digits, crumpled ears and mild joint contractures. Although mutations arise throughout FBN1, those clustering within exons 24-32 are associated with the most severe form of MFS, so-called neonatal MFS. All the mutations described in CCA occur in the "neonatal region" of FBN2. Both MFS and CCA are thought to arise via a dominant negative mechanism. The analysis of mouse mutations has demonstrated that fibrillin-1 microfibrils are mainly engaged in tissue homeostasis rather than elastic matrix assembly. In the current investigation, we have analysed the classical mouse mutant shaker-with-syndactylism using a positional candidate approach and demonstrated that loss-of-function mutations outside the "neonatal region" of Fbn2 cause syndactyly in mice. These results suggest that phenotypes distinct from CCA may result in man as a consequence of mutations outside the "neonatal region" of FBN2. 相似文献
43.
Exogenous antigens are generally presented by Class II major histocompatibility (MHC) molecules. When administered with an adjuvant, however, they are capable of inducing a CD8+ T-cell response where antigen recognition is associated with Class I MHC. Accordingly, immunization with soluble ovalbumin (OVA) alone does not activate CD8+ cytotoxic T cells (CTL) but when given in complete Freund's adjuvant (CFA), or in formulations of a number of novel adjuvants, an OVA-specific CD8+ CTL response can be detected. We show in this report that immunization with soluble OVA mixed with heat-killed Mycobacterium vaccae, but not with other common pathogenic and saprophytic mycobacteria, can activate OVA-specific CD8+ CTL. An OVA-specific CTL response is detected when mice are immunized by either the intraperitoneal or intranasal route and their spleen cells are re-stimulated in vitro. Adjuvant activity of heat-killed M. vaccae is present in M. vaccae culture filtrate, in soluble protein components of whole M. vaccae and in the 65 kDa heat-shock protein (hsp) of M. vaccae. Mycobacterium vaccae has previously been shown to have no adverse side-effects in humans. The current results suggest that M. vaccae may be useful as an adjuvant for vaccines and other immunotherapies where CD8+ CTL responses to exogenous proteins are crucial. 相似文献
44.
Gastrointestinal lymphoma 总被引:1,自引:0,他引:1
J M Skinner 《Pathology》1985,17(2):193-203
The gastrointestinal tract is the commonest site for primary extranodal malignant lymphoma. Despite this, gastrointestinal lymphomas are rare and present diagnostic and conceptual challenges. Principal among these are the differential diagnoses of malignant lymphoma and carcinoma and malignant lymphoma and pseudolymphoma, especially in the stomach; the nature of Mediterranean lymphoma and of the lymphoma complicating celiac disease; and the conceptual basis for differentiation of follicular centre cell lymphomas in the intestine. 相似文献
45.
46.
Production of the Kanagawa hemolysin by a strain of Vibrio parahaemolyticus isolated from a gastroenteritis patient was found to correlate with the presence in cell lysates of two unidentified compounds, designated X and Y. The two compounds were present in cell lysates of the organism grown in peptone at the optimal pH for hemolysin synthesis but were not present when cell lysates were grown in peptone at a constant pH of 8.0. They were also absent in cells grown in synthetic medium at pH 6.2 without the addition of D-tryptophan, a condition under which hemolysin is not produced. Both X and Y were present intracellularly only from the time that D-tryptophan was added to synthetic medium, a known method of inducing hemolysin synthesis. 相似文献
47.
48.
Detecting pre-ovulatory luteinizing hormone surges in urine 总被引:2,自引:1,他引:2
Kesner JS; Knecht EA; Krieg EF Jr; Wilcox AJ; O'Connor JF 《Human reproduction (Oxford, England)》1998,13(1):15-21
The study objectives were to determine (i) if pre-ovulatory luteinizing
hormone (LH) surges, undetected in urine by two immunoradiometric assays
(IRMA), were detectable by an ultrasensitive immunofluorometric assay
(IFMA) and (ii) the influence of creatinine adjustment on the detection and
timing of the urinary LH surges. Daily urine specimens were contributed by
healthy 25-36 year old volunteers during 14 ovulatory menstrual cycles for
an epidemiological study conducted in 1983-1985. Specimens were selected as
having been previously assayed by two IRMA without consistently detecting
LH surges. These urine specimens were remeasured using an IFMA and adjusted
for creatinine concentration. IFMA measurements revealed unambiguous LH
surges in all cycles. Adjusting IRMA urinary LH values for creatinine
concentrations revealed previously undetected LH surges in four of eight
cycles. Creatinine adjustment also altered the timing of IRMA and IFMA LH
surges by 1-5 days. These results demonstrate an IFMA that detects pre-
ovulatory LH surges in unpreserved, frozen urine from cycles where such
surges were previously undetectable. Further, creatinine adjustment can
markedly affect detection and timing of the onset and peak of the urinary
LH surge. While our analysis suggests that this adjustment improves the
validity of the LH measure, this requires further investigation.
相似文献
49.
The renal effects of i.v. saline loading equal to 1% body weight (b.wt.) were studied in 2 groups of rats: group I was anesthetized with Amytal (15 mg/100 g b.wt. plus supplementary doses), group II with Inactin (12.5-15.0 mg/100 g b.wt.). In group I the saline load caused an increase in urine flow (+92%), solute excretion (+67%), inulin clearance (CIN) (+24%), PAH clearance (+31%) and absolute proximal reabsorption rate (+27%). Proximal fractional reabsorption and filtration fraction (FF) remained unchanged, while plasma oncotic pressure (COP) decreased by 10%. Plasma renin fell and there was an inverse relationship between renin concentration and proximal reabsorption rate. In group II urine flow and solute excretion increased after saline (+85% and 110%, respectively); CIN and absolute proximal reabsorption rate was lower than in group I and failed to increase after saline. Proximal fractional reabsorption was also lower and decreased after saline. COP as well as renin decreased as in group I, but no relationship between renin concentration and proximal reabsorption rate could be demonstrated. The data indicate that Inactin depresses both resting proximal tubular reabsorptive capacity and the tubular response to a physiological volume expansion. The results are compatible with the hypothesis that the renin-angiotensin system is significantly involved in regulation of proximal tubular function, while they are incompatible with the idea that peritubular COP plays any major role in this adjustment. 相似文献
50.
Follicular fluid renin concentration and IVF outcome 总被引:1,自引:0,他引:1
C M Cornwallis S L Skinner P L Nayudu A Lopata R L Thatcher S P Yeung J A Whitworth 《Human reproduction (Oxford, England)》1990,5(4):413-417
Total renin protein concentration (TRC) was measured in stored follicular fluid (FF) samples from 42 women. Samples were selected according to their origin from follicles either without recovered ova ('empty', n = 38) or fertilized but with failed implantation ('failed', n = 36) or successful deliveries ('deliveries', n = 71). Ratios of number of embryos transferred to number of infants delivered were 2:1, 3:1 or 4:2 but 1:1 was not available. Non-parametric testing was applied to FF-TRC, volume and outcome. TRC was significantly higher in the delivery than the failed (P = 0.001) or empty (P = 0.002) categories. Assuming that the range of renin in failed follicles can identify the sub-population of unsuccessful follicles in the delivery category, then elevated FF-TRC was clearly associated with successful outcome. For individual women, the odds of infant delivery increased 17-fold as a function of average FF-TRC between 10,000 and 25,000 microIU/ml. For failed and delivery but not empty follicles, higher renin levels occurred in the smaller follicles, consistent with a burst of renin synthesis associated with the presence of an oocyte. The results suggest that FF-TRC relates to ovum viability with ovarian hyperstimulation and may have predictive use in IVF programmes. 相似文献