全文获取类型
收费全文 | 217329篇 |
免费 | 19375篇 |
国内免费 | 5061篇 |
专业分类
耳鼻咽喉 | 3303篇 |
儿科学 | 4146篇 |
妇产科学 | 3703篇 |
基础医学 | 18242篇 |
口腔科学 | 7462篇 |
临床医学 | 19733篇 |
内科学 | 20971篇 |
皮肤病学 | 2517篇 |
神经病学 | 11085篇 |
特种医学 | 5793篇 |
外国民族医学 | 14篇 |
外科学 | 21026篇 |
综合类 | 34382篇 |
现状与发展 | 10篇 |
一般理论 | 30篇 |
预防医学 | 28712篇 |
眼科学 | 2122篇 |
药学 | 20833篇 |
344篇 | |
中国医学 | 26288篇 |
肿瘤学 | 11049篇 |
出版年
2024年 | 998篇 |
2023年 | 4404篇 |
2022年 | 8320篇 |
2021年 | 10977篇 |
2020年 | 10603篇 |
2019年 | 12023篇 |
2018年 | 10443篇 |
2017年 | 9100篇 |
2016年 | 8151篇 |
2015年 | 7667篇 |
2014年 | 14671篇 |
2013年 | 14930篇 |
2012年 | 13125篇 |
2011年 | 14004篇 |
2010年 | 11263篇 |
2009年 | 9785篇 |
2008年 | 9072篇 |
2007年 | 9119篇 |
2006年 | 7704篇 |
2005年 | 6534篇 |
2004年 | 5423篇 |
2003年 | 4829篇 |
2002年 | 3717篇 |
2001年 | 3087篇 |
2000年 | 2744篇 |
1999年 | 2236篇 |
1998年 | 1813篇 |
1997年 | 1624篇 |
1996年 | 1336篇 |
1995年 | 1247篇 |
1994年 | 1146篇 |
1993年 | 1024篇 |
1992年 | 905篇 |
1991年 | 849篇 |
1990年 | 725篇 |
1989年 | 700篇 |
1988年 | 650篇 |
1987年 | 594篇 |
1986年 | 548篇 |
1985年 | 1809篇 |
1984年 | 2076篇 |
1983年 | 1302篇 |
1982年 | 1724篇 |
1981年 | 1204篇 |
1980年 | 1025篇 |
1979年 | 927篇 |
1978年 | 752篇 |
1977年 | 560篇 |
1976年 | 698篇 |
1975年 | 485篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
目的 探讨老年人急性阑尾炎的临床特点,更好地把握腹腔镜阑尾切除(LA)术的方法和特点。方法 回顾分析50例老年人急性阑尾炎LA的临床资料。结果 LA均获成功,患者全部治愈,无严重的并发症发生,肠功能恢复时间及住院时间均缩短。结论 老年人反应迟钝,阑尾炎进展快,易发生坏疽及穿孔,合并症多,手术风险较高,LA是安全、可行的,除个别腹膜后阑尾炎外,其余均可施行LA。 相似文献
32.
Summary— To investigate if the functional alterations observed in resistance arteries of spontaneously hypertensive rats (SHRs) were also present at the coronary level, in vitro experiments were performed in mesenteric resistance arteries (MRA) and in right (RIC) and left interventricular coronary (LIC) arteries taken from 15–25-week-old SHR and age-matched Wistar Kyoto rats WKYs. Using a passive extension protocol, internal diameters corresponding to 100 mmHg intraluminal pressure (D100) were determined and vessels were set up to a normalized internal diameter (0.9 D100). SHR mesenteric resistance arteries had a significantly smaller diameter compared to WKY arteries, whereas both types of SHR coronary arteries had a greater diameter compared to those of WKY rats. In arteries in the absence of contracting agonist, nitro-L-arginine (NOLA, 100 μM) induced a progressive rise in basal tone, which could be reversed by subsequent addition of L-arginine (100 μM) but not D-arginine (100 μM). When expressed as percent of maximal contractions induced by agonists (noradrenaline, NA [10 μM] in MRA; serotonin, 5-HT [10 μM], in RIC and LIC), these contractions were significantly stronger in WKY compared to SHR coronary and mesenteric resistance arteries. In NA-precontracted MRA and 5HT-precontracted coronary arteries in the presence of indomethacin (10 μM), the magnitude of acetylcholine-induced maximal relaxations (expressed as percent of maximal contractions induced by agonists) was greater in WKY compared to SHR arteries. After a 30-min incubation period, NOLA (100 μM) completely inhibited relaxations induced by acetylcholine (0.01–10 μM) in all types of precontracted arteries. Subsequent additions of sodium nitroprusside, (SNP, 10 μM) induced complete relaxations in all preparations. These results show that a basal release of NO or NO-like compound by endothelial cells is present in isolated mesenteric resistance and coronary arteries of WKY rats and SHRs. The contribution of endothelium-derived relaxing factor-nitric oxide (EDRF-NO) to arterial tone was lower in MRA compared to coronary arteries in both strains and in SHR compared to WKY arteries. In the SHR preparations, the impaired relaxation induced by acetylcholine appeared to be due to a functional alteration of the endothelium in the presence of normal reactivity of the smooth muscle cells. 相似文献
33.
Examined are several measures currently used in the assessment of child abuse, sexual abuse, and trauma. These measures include
structured clinical interviews, self report measures, screening inventory, symptom checklist, and some measures that include
decision making properties. Issues and implications for clinical practice are explored. 相似文献
34.
I. Hilakivi L. Ahtee J. O. Rinne T. Taira L. M. J. Attila P. Marjamäki 《Journal of neural transmission (Vienna, Austria : 1996)》1995,102(2):139-148
Summary Rats were treated with desipramine 5mg/kg, nomifensine 10mg/kg, zimelidine 25 mg/kg or with 0.9% sodium chloride once a day during the second and third weeks after birth, and brain stem, caudate/putamen and cortical monoamines, and caudate/putamen dopamine D1 (3[H]SCH 23390) and D2 (3[H]spiroperidol) receptor binding were measured when rats were at two months of age. In the brain stem, the concentration of 3-methoxy-4-hydroxy-phenyl glycol was increased in nomifensine rats and the ratio of 5-hydroxyindoleacetic acid to 5-hydroxytryptamine was increased in zimelidine rats. In the caudate/putamen, the concentrations of 3,4-dihydroxyphenylacetic acid and homovanillic acid and the ratio of homovanillic acid to dopamine were increased in desipramine rats; neither3[H]SCH 23390 nor3[H]spiroperidol binding were affected by any of the three monoamine uptake inhibiting antidepressants studied. In the cortex, the ratio of 5-hydroxyindoleacetic acid to 5-hydroxytryptamine was increased in desipramine and zimelidine rats. The findings suggest that desipramine but not nomifensine increases the metabolism of dopamine in the caudate/ putamen and nomifensine but not desipramine increases the metabolism of norepinephrine in the brain stem, and furthermore that the metabolism of serotonin is affected by desipramine as well as by zimelidine. It is possible that also treatment of women with these drugs during late pregnancy causes long-lasting changes in the brain of human fetus. 相似文献
35.
This article identifies common characteristics of educationally related programs that form a common basis for understanding and working with gifted programs. Special approaches and programs for educational enrichment as well as specific activities that have been successful are discussed. 相似文献
36.
Eiji Takeuchi Yuji Nimura Shin-ichi Mizuno Hideaki Suzuki Shinsuke Iyomasa Masaki Terasaki Hiroshi Kuriki Keiko Tamiya-Koizumi Shonen Yoshida 《Journal of Hepato-Biliary-Pancreatic Surgery》1997,4(3):254-262
Hepatocyte regeneration has been widely investigated, with the mitotic index and the incorporation of [3H]thymidine being used as regeneration markers. We focused on the induction of DNA replication enzymes, particularly DNA polymerases
(pol) α, δ, and ε. Using rat models, we have shown that the activity of pol α in crude liver extract well represents the regenerating
capacity of hepatocytes. Using pol α as an indicator, we analyzed liver regeneration in rat models under various conditions:
obstructive jaundice, external or internal biliary drainage, and the obstruction of portal vein branches. It has been revealed
that the ligation of the common bile duct alone induces a certain amount of hepatocyte proliferation. It was striking that
external biliary drainage suppressed regeneration capacity in cholestatic rat liver after partial hepatectomy. The strong
regeneration in nonligated lobes induced by portal branch ligation was similar to the liver regeneration seen after partial
hepatectomy with respect to the induction of DNA polymerases. Taken together, the aspects of DNA replication, particularly
the induction of DNA polymerases, may contribute to shedding new light on the regeneration of human liver.
This work was supported in part by a Grant-in-Aid for General Scientific Research and for Cancer Research from the Ministry
of Education, Science and Culture, Japan, and by grants from the Uehara Memorial Foundation 相似文献
37.
Klaus Edvardsen Nils Brünner Mogens Spang-Thomsen Frank S. Walsh Elisabeth Bock 《International journal of developmental neuroscience》1993,11(5)
A cDNA encoding a transmembrane 140 kDa isoform of the neural cell adhesion molecule, NCAM, was transfected into the rat glioma cell line BT4Cn. Transfectants with a homogeneously high expression of NCAM-B showed a decreased capacity for penetration of an artificial basement membrane when compared to cells transfected with expression-vector alone or untransfected cells. However, when injected subcutaneously into nude mice, both NCAM expressing cells and control cells produced invasive tumors. Nude mice injected with NCAM positive cells developed tumors with slower growth rates as compared to those induced by NCAM negative cells. This implies that NCAM may not only be involved in adhesive and motile behaviour of glioma cells, but also in their growth regulation. 相似文献
38.
Martin F. Ward Angie Titchen Clare Morrell Brendan McCormack Alison Kitson 《Journal of clinical nursing》1998,7(1):29-36
? The paper describes a multiproject practice development programme undertaken over a period of 1 year. ? The background and development of the programme are outlined, whilst attention is paid to the innovatory nature of the work, particularly the use of inductive, deductive and integrated approaches to both change implementation and project supervision. ? The programme was monitored throughout using different data sources and the paper uses evaluative material retrospectively to provide answers to organizational and professional difficulties which arose during the course of the programme. ? The authors conclude that the use of combinations of different models for practice development has potential, but requires careful supervision. ? They also recommend that those involved in practice development are made fully aware of its local or micropolitics, and develop strategies to deal with change before it occurs, not after it has taken place. 相似文献
39.
J. Pepke-Zaba T. W. Higenbottam A. T. Dinh Xuan J. P. Scott T. A. H. English J. Wallwork 《Transplant international》1990,3(1):108-112
Abstract. Twenty-one patients were studied at rest and during exercise after heart transplantation to compare cardiac output measured by thermodilution and impedance cardiography. Exercise was performed on a bicycle ergometer over a limited range of work load (25 and 50 watt) whilst metabolic gas exchange was recorded. One patient was studied at rest whilst his circulation was maintained by a Jarvik-7 artificial heart. The values of cardiac output measured by impedance cardiography corresponded closely with the flow rate from the artificial heart. There was also close agreement between the impedance and thermodilution measurements of cardiac output at rest and during exercise. Both measurements followed the changes in heart rate and oxygen consumption. Both thermodilution and impedance cardiography methods elicited good reproducibility of cardiac output measurements at rest and during exercise. These observations suggest that the noninvasive and continuous record of cardiac output obtained by impedance cardiography can be used for the postoperative monitoring of heart transplant recipients. 相似文献
40.
The conversion of multiple whole blood donors to apheresis donors is a challenge since a rapidly expanding apheresis donor base could erode homologous collections. We addressed this concern with a plan to enhance apheresis recruitment as well as donations among homologous donors with types O and B blood. Focusing the donor's attention on blood type as it relates to type-specific product needs was the basis of our approach. A matrix was used to recruit the desired types for the desired procedures (whole blood, platelet/plasma apheresis). The matrix instructed donors of blood types O, A-, and B- to primarily give whole blood and to give apheresis as a secondary donation. Donors AB, A+, and B+ were primarily directed to apheresis donations, whole blood donation being secondary. A+ and O- donors only gave their secondary donation if they were at maximum donations with the primary donation. The collections by blood type in percentages for 12 months of 1992/93 for whole blood were O+ 38.9, 0- 7.3, A+ 29.5, A- 5.7, B+ 11.9, B- 2.1, AB+ 3.7, AB+ 0.7. For apheresis it was 0+ 36.2, 0- 6.7, A+ 33.0, A- 6.6, B+ 10.4, B- 1.2, AB+ 4.9, AB+ 1.0. In 1992/93, A+ and B+ apheresis collections as compared to total apheresis collections increased by 4.9% and 13.7%, respectively. For O group apheresis donations, a decrease of 2.5% was shown and A+ whole blood donations decreased by 5.35%. During the same period of time, total apheresis collections increased by 3,058 units. We demonstrated that integration of apheresis recruitment with type-specific whole blood recruitment yielded significant increases of type-specific products. 相似文献