全文获取类型
收费全文 | 18876篇 |
免费 | 1013篇 |
国内免费 | 56篇 |
专业分类
耳鼻咽喉 | 190篇 |
儿科学 | 436篇 |
妇产科学 | 411篇 |
基础医学 | 2776篇 |
口腔科学 | 538篇 |
临床医学 | 1715篇 |
内科学 | 3632篇 |
皮肤病学 | 622篇 |
神经病学 | 2048篇 |
特种医学 | 750篇 |
外科学 | 2538篇 |
综合类 | 58篇 |
一般理论 | 3篇 |
预防医学 | 1057篇 |
眼科学 | 411篇 |
药学 | 1455篇 |
中国医学 | 58篇 |
肿瘤学 | 1247篇 |
出版年
2023年 | 81篇 |
2022年 | 75篇 |
2021年 | 198篇 |
2020年 | 161篇 |
2019年 | 189篇 |
2018年 | 319篇 |
2017年 | 329篇 |
2016年 | 399篇 |
2015年 | 401篇 |
2014年 | 417篇 |
2013年 | 636篇 |
2012年 | 1021篇 |
2011年 | 1066篇 |
2010年 | 622篇 |
2009年 | 610篇 |
2008年 | 1036篇 |
2007年 | 1111篇 |
2006年 | 1102篇 |
2005年 | 1137篇 |
2004年 | 1079篇 |
2003年 | 1027篇 |
2002年 | 1079篇 |
2001年 | 537篇 |
2000年 | 537篇 |
1999年 | 480篇 |
1998年 | 235篇 |
1997年 | 165篇 |
1996年 | 138篇 |
1995年 | 117篇 |
1994年 | 116篇 |
1993年 | 89篇 |
1992年 | 201篇 |
1991年 | 177篇 |
1990年 | 191篇 |
1989年 | 168篇 |
1988年 | 152篇 |
1987年 | 135篇 |
1986年 | 139篇 |
1985年 | 129篇 |
1984年 | 120篇 |
1983年 | 99篇 |
1979年 | 118篇 |
1978年 | 86篇 |
1977年 | 78篇 |
1974年 | 91篇 |
1973年 | 93篇 |
1972年 | 86篇 |
1971年 | 78篇 |
1969年 | 87篇 |
1968年 | 91篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
F. Gebhard M. Marzinzig U. B. Brückner W. Hartel 《Langenbeck's archives of surgery / Deutsche Gesellschaft fur Chirurgie》1997,382(5):243-251
In a prospective study, the systemic inflammatory consequences of surgery-induced lung tissue injury were evaluated using biochemical markers. The aim was to examine whether this type of injury produces a specific pattern of prostanoid plasma levels (prostacyclin, thromboxane, PGE2, PGF2α, and PGM). We, therefore, compared 18 patients (group 1) who underwent thoracotomy without injury to the lung with 26 patients (group 2) that had a resection of pulmonary tissue due to benign diseases. Group 2 patients clearly revealed increased plasma levels of C-reactive protein as well as of the granulocyte-specific PMN-elastase. In particular, there was a pronounced release of prostacyclin and its antagonist thromboxane A2 following lung tissue resection. In contrast to group 1 patients, lung tissue damage resulted in immediately elevated plasma levels of PGF2α and PGE2. When, however, taking into account the time course of PGM, the stable cleavage product of PGF2α, there was no hint of an altered pulmonary metabolic capacity. Presumably, this pattern of elevated prostanoid levels in group 2 is the result of the surgical damage to the lung tissue. Therefore, it can be suggested to be specific for that type of injury. Thus, the release of prostanoids following surgery-induced lung tissue damage may indicate the importance of these mediators, particularly in thoracic injuries associated with lung damage since those may lead to post-traumatic pulmonary dysfunction. These substances may also be useful in evaluating both the severity and the extent of lung tissue damage following major trauma. 相似文献
62.
63.
Kurt Brändle Norbert Degen 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1994,102(2):272-286
According to Sperry's chemoaffinity hypothesis, the projection of a small eye fragment with a reduced amount of optic fibres should be restricted to that position in the optic tectum corresponding to its own specificity. However, previous investigations on different types of quarter-eyes in Xenopus laevis have revealed that their retinal projection was always restricted to the rostral part of the tectum, no matter what the origin of the remaining retinal quadrant. To get an indication of the state of specificity in such eye fragments, we investigated by electrophysiological and histological methods several features of the retinal projections of temporoventral (TV), naso-ventral (NV) and ventral (V) quarter-eyes which referred to their positional identity. Irrespective of their different origins, the projections were always located in the rostral part of the tectum, the size of the innervated tectal area depending for all fragment types on the size of the quarter-eyes, i.e. number of optic fibres. However, quantitative analyses revealed that with increasing eye size the various fragments expand their projections preferentially into those tectal areas that match their original specificity: TV projection is more concentrated in the rostral tectum, NV eyes expand their projections mainly to the caudal tectum, and V eyes enlarge their projections equally into the medial and caudal tectum. In addition, fibre-tracing experiments with cobaltic lysine showed that, according to the different origins of the quarter-eyes, retinal fibres follow the appropriate branch of the optic tract selectively: fibres of NV and V eyes pass mainly through the medial tract, and most fibres of TV eyes innervate the rostral tectum directly from a central position between the two side branches. All these findings suggest that the different types of quarter-eyes retain their original positional identity. Thus, their rostrally located retinotectal projections are not in register with their retinal specificity. We conclude that in X. laevis local positional markers in the tectum, if present at all, do not influence the development of the retinotectal projection. Instead we suggest a concept of self-sorting of the optic fibres, which can account for the partial innervation of the rostral tectum in different types of quarter-eyes. 相似文献
64.
Infection of peripheral mononuclear blood cells by hepatitis C virus. 总被引:25,自引:0,他引:25
A L Zignego D Macchia M Monti V Thiers M Mazzetti M Foschi E Maggi S Romagnani P Gentilini C Bréchot 《Journal of hepatology》1992,15(3):382-386
We investigated the infection of peripheral blood mononuclear cells (PBMNC) by hepatitis C virus (HCV) in 5 patients with HCV-related chronic hepatitis. The presence of HCV-RNA-positive and -negative strands was tested with the polymerase chain reaction (PCR) method. In all subjects, HCV-RNA was shown in PBMNC. In 3 cases, HCV-RNA was shown in the T- and B-cell populations, with viral RNA also present in the monocyte-macrophage fraction of two of these. HCV-RNA-negative stranded molecules, indicative of the viral multiplication, were significantly increased in cells maintained in cultures with PHA/PMA stimulation. The results indicate that HCV infect blood mononuclear cells, thus suggesting that this cellular tropism may play a role in HCV infection. 相似文献
65.
Angela Ohlemacher Rainer Schenk Hans Peter Weitzel Nikolai Tyutyulkov Maria Tasseva Klaus Müllen 《Macromolecular chemistry and physics.》1992,193(1):81-93
The energy gaps of poly(p-arylenevinylene)s with phenylene, naphthylene and anthrylene subunits are determined by extrapolating the UV/VIS spectroscopic data of the oligomers. The band structure of the three polymers was theoretically investigated. The topology-, geometry- and correlation-factors were determined upon which the energy spectra of this class of one-dimensional π-electron systems depend. 相似文献
66.
Thrombin Inhibition in discordant xenograft rejection 总被引:1,自引:0,他引:1
Beth-Ann Lesnikoski Daniel Candinas Ichiro Otsu Rainer Metternich Fritz H. Bach Simon C. Robson 《Xenotransplantation》1997,4(3):140-146
Abstract: Microvascular thrombosis and the associated platelet and endothelial cell activation are prominent observations in xenograft rejection. This pathological picture could be related to the excessive generation of thrombin in the context of either inflammation or putative inter-species molecular incompatibilities between activated coagulation factors and their natural anticoagulants. Relatively selective thrombin Inhibition with the serine protease inhibitor SDZ MTH 958 (MTH-958) are independent of heparinoids and anti-thrombin III. MTH-958 has been shown to significantly prolong porcine cardiac function during perfusion with human blood in an ex vivo model. The aim of this study was to validate the role of thrombin generation in a rodent model of discordant xenograft rejection in vivo. The effect of thrombin inhibition with MTH-958 was tested in both hyperacute rejection (HAR) and delayed xenograft rejection (DXR) after decomplementation with cobra venom factor (CVF) in normal Lewis (Lew) rats and Intrinsic C6 deficiency In PVG (C6-/PVG) recipient rats. Recipient rats received heterotopic guinea pig cardiac xenografts and were treated with titrated doses of MTH-958 until the time of graft rejection. Plasma samples at selected time points were examined to confirm effective thrombin inhibition, and rejected grafts were analyzed by immunohistology. MTH-958 significantly improved graft survival in HAR albeit the extent of prolongation was not marked, but the agent failed to prolong survival In CVF-treated Lew rats. In C6-/PVG rats receiving MTH-958, a significantly reduced graft survival time was observed when compared with C6-/PVG controls. The grafts from MTH-958-treated animals showed dense deposits of C3, IgM, and IgG with fibrin levels similar to controls. The thrombin antagonist tested could prolong xenograft survival during HAR but had no benefit in DXR. The relative non-specificity of the serine protease inhibitor MTH-958 with the potential activation of alternative pathway of complement via the inhibition of factor I could account for the failure to prolong xenograft survival in DXR. The pathogenetic significance of thrombin generation in this situation remains to be determined by the use of more selective and pharmacologically acceptable I anti-thrombin agents. 相似文献
67.
68.
Rainer O. Seidl Ingo Todt Arne Ernst 《European archives of oto-rhino-laryngology》2007,264(3):291-293
We report on a case of esophageal atresia following cervical spine surgery. A swallowing examination was performed using fibre-optic
endoscopy and videofluoroscopy. There was scar tissue fixation of the larynx and esophagus to the cervical spine. Operative
mobilization of the larynx and esophagus and formation of a sliding layer using a platysma-fascia flap was done. The PEG and
tracheal cannula were removed; oral nutrition was initiated after 3 months. Swallowing disorders following operations on the
upper cervical spine should be investigated. Careful preparation that preserves the layers should be carried out. Fixation
of tissues as a result of scarring should be treated with a sliding layer. 相似文献
69.
Dr. Rainer Braunschweig Oliver Schilling Wolfgang Wawro Martin Herrmann 《Trauma und Berufskrankheit》2003,5(2):156-162
Projection radiographic techniques have been used in a standardized manner for decades for the diagnosis of conditions of the foot and ankle; the indications for them and the pattern of findings useful in the initial diagnosis and monitoring of the course are generally known to clinical radiology staff. Computed tomography has been introduced as an extension of the basic procedures performed for diagnosis in the ankle and the hindfoot. In the case of complex fractures, however, specialist experience is essential. CT is an easily accessible investigative procedure and is meanwhile economical and very powerful. Magnetic resonance imaging supplements the range of investigations in special cases when there are particular problems. Microfractures, findings indicative of inflammation and/or dystrophy and, in particular questions concerning the musculoligamentous support system are the situations in which such investigations are needed. Ultrasound has an additive value vis-à-vis magnetic resonance imaging and is an easily accessible and highly effective examination procedure both for the primary diagnosis and for serial monitoring. Financial constraints in the healthcare sector are increasingly limiting purely medical indications. Regardless of this development, the retention of projection radiography, computer tomography, and magnetic resonance imaging must be demanded for the initial diagnosis in the care of foot and ankle injuries. The earliest possible implementation of all these techniques for the initial diagnosis is the first step towards effective treatment. Cafrefully chosen and, if appropriate, complementary strategies are needed for monitoring of the course and for assessment. 相似文献
70.