全文获取类型
收费全文 | 230326篇 |
免费 | 19307篇 |
国内免费 | 9252篇 |
专业分类
耳鼻咽喉 | 1593篇 |
儿科学 | 4854篇 |
妇产科学 | 2829篇 |
基础医学 | 28405篇 |
口腔科学 | 3504篇 |
临床医学 | 22429篇 |
内科学 | 42875篇 |
皮肤病学 | 1760篇 |
神经病学 | 8139篇 |
特种医学 | 6084篇 |
外国民族医学 | 38篇 |
外科学 | 26594篇 |
综合类 | 36801篇 |
现状与发展 | 33篇 |
一般理论 | 25篇 |
预防医学 | 14059篇 |
眼科学 | 4769篇 |
药学 | 23012篇 |
141篇 | |
中国医学 | 12709篇 |
肿瘤学 | 18232篇 |
出版年
2024年 | 587篇 |
2023年 | 3451篇 |
2022年 | 6554篇 |
2021年 | 8792篇 |
2020年 | 8225篇 |
2019年 | 7756篇 |
2018年 | 7570篇 |
2017年 | 7762篇 |
2016年 | 8363篇 |
2015年 | 8137篇 |
2014年 | 12950篇 |
2013年 | 13960篇 |
2012年 | 11685篇 |
2011年 | 13330篇 |
2010年 | 11244篇 |
2009年 | 10980篇 |
2008年 | 11032篇 |
2007年 | 12013篇 |
2006年 | 11325篇 |
2005年 | 10780篇 |
2004年 | 9218篇 |
2003年 | 8218篇 |
2002年 | 6347篇 |
2001年 | 6087篇 |
2000年 | 4948篇 |
1999年 | 4475篇 |
1998年 | 3387篇 |
1997年 | 3057篇 |
1996年 | 3054篇 |
1995年 | 2850篇 |
1994年 | 2578篇 |
1993年 | 2291篇 |
1992年 | 2031篇 |
1991年 | 1716篇 |
1990年 | 1447篇 |
1989年 | 1346篇 |
1988年 | 1265篇 |
1987年 | 983篇 |
1986年 | 763篇 |
1985年 | 895篇 |
1984年 | 879篇 |
1983年 | 553篇 |
1982年 | 687篇 |
1981年 | 596篇 |
1980年 | 499篇 |
1979年 | 426篇 |
1978年 | 360篇 |
1977年 | 300篇 |
1976年 | 329篇 |
1975年 | 200篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
992.
Akbar F Heinonen S Pirskanen M Uimari P Tuomainen TP Salonen JT 《Molecular human reproduction》2005,11(1):73-77
Association between pre-eclampsia (PEE1) and the dimethylarginine dimethylaminohydrolase (DDAH) 1 and 2 genes, which play a role in the regulation of nitric oxide synthesis and release, was studied. In a case-control study design single nucleotide polymorphisms (SNPs) were determined at eight sites in the DDAH1 gene and at one site (Pro231Pro) in the DDAH2 gene from 132 women with pre-eclampsia and 112 healthy controls. Three SNPs in the DDAH1 gene were associated with pre-eclampsia, showing complete linkage disequilibrium with each other, but none of the associations in the allele or genotype data reached statistical significance in either of the genes after the correction for multiple testing. Haplotype frequencies were estimated using a population based on a maximum likelihood method (EM algorithm). Four common DDAH1 haplotypes were present and a significant association of haplotypes H2 and H3 with pre-eclampsia (P=0.03) was found. The risk of pre-eclampsia was greatest in individuals (odds ratio: 3.93; 95% confidence interval: 1.54-9.99) who had two copies of the high-risk haplotypes (H2 or H3). The observed haplotypic association provides the first evidence of the importance of DDAH1 polymorphisms in pre-eclampsia susceptibility. 相似文献
993.
Human sperm chemotaxis: both the oocyte and its surrounding cumulus cells secrete sperm chemoattractants 总被引:5,自引:0,他引:5
Sun F Bahat A Gakamsky A Girsh E Katz N Giojalas LC Tur-Kaspa I Eisenbach M 《Human reproduction (Oxford, England)》2005,20(3):761-767
BACKGROUND: Human sperm chemotaxis to pre-ovulatory follicular fluid is well established in vitro. However, it is not known whether the female's oocyte-cumulus complex secretes sperm chemoattractants subsequent to ovulation (for enabling sperm chemotaxis within the Fallopian tube) and, if so, which of these cell types--the oocyte or the cumulus oophorus--is the physiological origin of the secreted chemoattractant. METHODS: By employing a directionality-based chemotaxis assay, we examined whether media conditioned with either individual, mature (metaphase II) human oocytes or the surrounding cumulus cells attract human sperm by chemotaxis. RESULTS: We observed sperm chemotaxis to each of these media, suggesting that both the oocyte and the cumulus cells secrete sperm chemoattractants. CONCLUSIONS: These observations suggest that sperm chemoattractants are secreted not only prior to ovulation within the follicle, as earlier studies have demonstrated, but also after oocyte maturation outside the follicle, and that there are two chemoattractant origins: the mature oocyte and the surrounding cumulus cells. 相似文献
994.
Chun Chang John Lipian Dennis A. Barnes Larry Seger Cheryl Burns Brian Bennett Laura Bonney Larry F. Rhodes George M. Benedikt Robert Lattimer Shyhchang S. Huang Victor W. Day 《Macromolecular chemistry and physics.》2005,206(19):1988-2000
Summary: Homopolymers of a bis‐trifluorocarbinol substituted norbornene ( 1 ) (α,α‐bis(trifluoromethyl)bicyclo[2.2.1]hept‐5‐ene‐2‐ethanol or HFANB) and copolymers of 1 with t‐butyl ester of 5‐carboxylic acid ( 2 , t‐BuEsNB) were produced using palladium catalysts and olefinic chain transfer agents such as 1‐hexene and ethylene to control molecular weight. However, these low‐molecular‐weight polymers exhibited relatively low optical transparencies at 193 nm. In fact, the opacity (measured as optical densities in absorbance units per micron) of thin films of these homo‐ and co‐polymers was inversely proportional to their molecular weight. This relationship is consistent with an end group contribution to the film opacity. Spectroscopic analysis of these polymers by 1H NMR and MALDI‐TOF MS confirmed that 1‐hexene and ethylene chain transfer agents generated olefin‐terminated vinyl addition polymers. The olefinic end group contribution to optical density can be eliminated by appropriate chemical modification. Both epoxidation and hydrogenation of the polymer olefinic end groups generated very low optical density materials, independent of molecular weight, that are suitable as 193‐nm photoresist binder resins.
995.
Schistosomiasis: an unusual cause of tubal infertility 总被引:3,自引:0,他引:3
Balasch Juan; Martinez-Roman Sergio; Creus Montserrat; Campo Elias; Fortuny Albert; Vanrell Juan A. 《Human reproduction (Oxford, England)》1995,10(7):1725-1727
A case report of a Nigerian woman having an unusual cause oftubal infertility is presented. On histological examinationof the Fallopian tube, ova of Schistosoma haematobium enclosingliving miracidia were found in the smooth muscle layer of theFallopian tube and its mesosalpinx. Mechanisms of tubal involvementare analysed. The case indicates the need to consider schisto-somiasisas a possible aetiological factor in patients with tubal infertilitycoming from areas where the disease is endemic. 相似文献
996.
Gordon Lauc Annie-Pierre Seve Jean Hubert Mirna Flgel-Mrsic Werner E. G. Müller Heinz C. Schrder 《Mechanisms of ageing and development》1993,70(3):227-236
Previous studies have demonstrated the existence of nuclear carbohydrate binding proteins in a variety of mammalian cells with molecular masses of 35 000, 67 000, and 70 000 (CBP35, CBP67, and CBP70), which are associated with nuclear ribonucleoprotein (RNP) complexes. CBP35 consists of two domains, an aminoterminal portion that is homologous to certain regions of proteins of the heterogeneous nuclear RNP complex, and a carboxyl-terminal portion homologous to β-galactoside-specific lectins. CBP35 it has been proposed, like the glucose-specific lectin, CBP67, to guide RNP complexes through the nuclear pore. Here we show that the exposure of mature rats to stress induces an increase in nuclear CBP35 bound to CBP67 and retained on immobilized glucose. Nuclear extracts from the livers of old rats displayed no detectable stress response. This CBP35·CBP67 association detected in rat liver is considered with respect to the CBP35·CBP70 association recently observed in HL60 cell nuclear extracts. 相似文献
997.
Jos Angel Gonzalo Ana Gonzlez-García Terje Kalland Gunnar Hedlund Carlos Martínez-A Guido Kroemer 《European journal of immunology》1993,23(9):2372-2374
Intravenous injections of 50 μ.g Staphylococcus aureus enterotoxin B (SEB) or bacterial lipopolysaccharide (LPS) are lethal, provided that mice are simultaneously sensitized with either N-galactosamine (GalN) or the anti-glucocorticoid RU-38486. Similar to the synthetic glucocorticoid (GC) receptor agonist dexamethasone, pharmacological doses of the immunomodulator linomide (quinoline-3-carboxamide) prevent death in all four models of lethal septic shock (LPS + GalN, LPS + RU-38486, SEB + GalN, and SEB + RU-38486) and inhibit the secretion of tumor necrosis factor, one of the major intermediate effector molecules of SEB and LPS toxicity. In this system, cyclosporine A (CsA), although effective in suppressing SEB toxicity, fails to counteract the lethal effect of LPS. This observation, together with the fact that linomide acts in the presence of excess amounts of GC receptor antagonist, indicates that linomide functions in a different way to that of known immunosuppressive agents like CsA and GC. 相似文献
998.
S. A. Kurilovich E. V. Pozdeeva A. P. Serdyuk I. O. Svetlova Yu. A. Shakhov 《Bulletin of experimental biology and medicine》1990,110(6):1660-1663
Institute of Therapy, Siberian Branch, Academy of Medical Sciences of the USSR, Novosibirsk. All-Union Preventive Medicine Research Center, Ministry of Health of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR Yu. P. Nikitin.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 110, No. 12, pp. 611–613, December, 1990. 相似文献
999.
Sh. K. Kurbanov Ch. R. Alimhodzhaeva 《Bulletin of experimental biology and medicine》1979,87(5):421-423
The enzyme spectrum of pancreatic homogenate was studied in acute experiments on male albino rats during adaptation for 30 days to muscular exertion (forced swimming in water at a temperature of 32±1°C), heat (hyperthermia to 40–41°C), and cold (cooling to 3–4°C) for 3 h. The initial periods of adaptation to these factors (second-twelfth day) were shown to be characterized by a considerable decrease in activity of all the enzymes studied, but later, with adaptation of the animals to these factors, enzyme activity was restored to its original level (18th–24th day), and remained more or less constant until the end of the experiment (30th day). It is suggested that changes in the enzyme spectrum of the pancreas are brought about through the participation of the hypothalamo-hypophyseo-adrenal system in accordance with the principle of the general adaptation syndrome.Laboratory of the Physiology of Digestion and Laboratory of General Physiology, Institute of Physiology, Academy of Sciences of the Uzbek SSR, Tashkent. (Presented by Academician of the Academy of Sciences of the USSR O. G. Gazenko.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 87, No. 5, pp. 412–414, May, 1979. 相似文献
1000.
The occurrence of Chlamydia trachomatis in the semen of men participating in an IVF programme 总被引:1,自引:0,他引:1
Nagy Balint; Corradi Gyula; Vajda Zoltan; Gimes RezsO; Csomor Sandor 《Human reproduction (Oxford, England)》1989,4(1):54-56
Chlamydia trachomatis is one of the most common causative agentsof sexually transmitted diseases. The authors studied the occurrenceof C.trachomatis in the semen of 184 asymptomatic men participatingin the IVF programme. Twenty-six (14.1%) of the 184 tested werepositive for C.trachomatis, these patients and their wives receivingdoxycycline capsules twice, 100 mg on the first day and 100mg/day for the following 13 days. This treatment was effectivein 88.5% of the cases and in the rest, treatment continued witherithromycin 250 mg four times/day for 2 weeks. The authorscompared the semen parameters (cell count, motility, morphology,bovine mucus penetration and hypo-osmotic swelling test) inthe infected and non-infected groups and observed no significantdifference between these two groups 相似文献