全文获取类型
收费全文 | 1155篇 |
免费 | 118篇 |
国内免费 | 53篇 |
专业分类
耳鼻咽喉 | 3篇 |
儿科学 | 40篇 |
妇产科学 | 3篇 |
基础医学 | 277篇 |
口腔科学 | 19篇 |
临床医学 | 179篇 |
内科学 | 235篇 |
皮肤病学 | 9篇 |
神经病学 | 38篇 |
特种医学 | 99篇 |
外科学 | 130篇 |
综合类 | 57篇 |
预防医学 | 93篇 |
眼科学 | 6篇 |
药学 | 62篇 |
中国医学 | 1篇 |
肿瘤学 | 75篇 |
出版年
2021年 | 11篇 |
2019年 | 17篇 |
2018年 | 15篇 |
2017年 | 11篇 |
2016年 | 9篇 |
2015年 | 16篇 |
2014年 | 19篇 |
2013年 | 26篇 |
2012年 | 39篇 |
2011年 | 44篇 |
2010年 | 30篇 |
2009年 | 25篇 |
2008年 | 36篇 |
2007年 | 78篇 |
2006年 | 43篇 |
2005年 | 42篇 |
2004年 | 31篇 |
2003年 | 36篇 |
2002年 | 32篇 |
2001年 | 33篇 |
2000年 | 28篇 |
1999年 | 23篇 |
1998年 | 31篇 |
1997年 | 20篇 |
1996年 | 33篇 |
1995年 | 19篇 |
1994年 | 25篇 |
1993年 | 27篇 |
1992年 | 26篇 |
1991年 | 30篇 |
1990年 | 21篇 |
1989年 | 23篇 |
1988年 | 21篇 |
1987年 | 38篇 |
1986年 | 24篇 |
1985年 | 31篇 |
1984年 | 28篇 |
1983年 | 23篇 |
1982年 | 15篇 |
1981年 | 23篇 |
1980年 | 12篇 |
1979年 | 19篇 |
1978年 | 12篇 |
1977年 | 11篇 |
1976年 | 14篇 |
1974年 | 11篇 |
1973年 | 12篇 |
1971年 | 9篇 |
1970年 | 8篇 |
1969年 | 9篇 |
排序方式: 共有1326条查询结果,搜索用时 15 毫秒
1.
Tissue expansion is a well-established technique for the management of soft tissue deficiencies. In congenital hand surgery the construction of an adequate first web is paramount. We used tissue expansion in four hands in three patients with complete complex syndactyly of the first web space. Two of these patients had Apert's syndrome and the other an isolated mitten hand anomaly. The expander is preferably placed early in life so that first web construction is completed in the first year. Tissue expander ports are left exposed. There have been no infections, flap or expander loss in our series. 相似文献
2.
Oxygen-free radical production and reperfusion injury are complex mechanisms. New and improved methods for maximizing the benefits of reperfusion while minimizing reperfusion injury are on the horizon in the 1990s. Critical care nurses play a crucial role in the assessment, planning, and intervention of patients experiencing the deleterious effects of free radicals and reperfusion injury. Thus, a sound knowledge base in the pathophysiology of reperfusion injury, the detrimental effects of free radicals, and the potential benefits of free-radical scavengers is essential. 相似文献
3.
Uroscopy in the 21st century: high-field NMR spectroscopy 总被引:1,自引:1,他引:0
Neild GH; Foxall PJ; Lindon JC; Holmes EC; Nicholson JK 《Nephrology, dialysis, transplantation》1997,12(3):404-417
From the experiments described, it can be seen that there are different
research approaches that can be taken and these are summarized in Table 1.
Whereas much scientific research is principally hypothesis led, there
remains, nevertheless, an important place for exploratory research. High
resolution NMR can measure, directly and simultaneously, a wide range of
endogenous metabolites in biological fluids and has the unique capability
of providing structural information on the metabolites detected. It has
proved to be a powerful research tool with which to study inherited
metabolic diseases, renal disease, drug metabolism, and toxicity, and can
be used to monitor the effects of drug therapy. For instance, by using a
library of experimental toxins one can map the metabolic profile of
site-specific nephron injury. With this approach in man one could
eventually take an unknown disease such as Balkan nephropathy and predict
the initial site of tubular injury, the mode of injury and therefore the
kind of toxin capable of producing that injury. NMR spectroscopic
techniques are still advancing rapidly, with ever increasing sensitivity
and sophistication of NMR pulse sequences to enhance structural elucidation
in complex mixtures. Given the advances in directly coupled HPLC-NMR and
even HPLC-NMR-mass spectroscopy it is likely that these technologies in
conjunction with pattern recognition will make major contribution to our
understanding of renal processes and provide new diagnostic insights in the
21st century.
相似文献
4.
5.
Structure-activity relationships for epidermal ornithine decarboxylase induction and skin tumor promotion by anthrones 总被引:2,自引:0,他引:2
DiGiovanni John; Kruszewski Francis H.; Coombs Maurice M.; Bhatt Tarlochan S.; Pezeshk Abbas 《Carcinogenesis》1988,9(8):1437-1443
The present study was designed to compare the skin tumor promotingand epidermal ornithine decarboxylase (ODC) inducing activitiesof various structural analogs of anthralin (1, 8-dihydroxy-9-anthrone)and chrysarobin (1, 8-dihydroxy-3- methyl-9-anthrone). Groupsof 30 SENCAR mice each were initiated with 7, 12-dimethylbenz[a]anthraceneand 2 weeks later promoted with once- or twice-weekly applicationsof various doses of these anthrone derivatives. Carbon-10 (C10)-acylderivatives of anthralin were active skin tumor promoters inthe range of 25440 nmol per mouse. 10-Acetylanthralinwas significantly more active than 10-myristoyl-anthralin atlow doses (e.g. 25 and 50 nmol per mouse) and nearly as potentas the unsubstituted compound. Higher doses ( 100 nmol per mouse)of this derivative were toxic, hence, reducing the final papillomaresponse. On a relative activity scale where anthralin is 1.0,these derivatives had activities that were 0.7 and 0.2, respectively.10, 10-Dipropylanthralin was totally inactive at the doses tested.C6-Substituted derivatives of chrysarobin demonstrated diversetumor promoting activities when tested in the range of 25440nmol per mouse. On a relative activity scale where chrysarobinis 1.0, 6-methoxychrysarobin (physcion anthrone) was 0.9, whereas6-hydroxychrysarobin (emodin anthrone) had no activity. Chrysophanicacid (1, 8-dihydroxy-3-methyl-9, 10-anthraquinone) was alsoinactive as a tumor promoter at the doses tested. In general,the tumor promoting activities of these anthrone derivativescorrelated very well with their ability to induce epidermalODC after a single topical application indicating an importantrole for this enzyme in skin tumor promotion by anthones. Theability of C10-substituted derivatives of anthralin to undergobase catalyzed oxidation in vitro correlated with both ODC inducingand tumor promoting activities. In addition, copper(II) bis(diisopropylsalicylate)was found to inhibit both ODC induction and skin tumor promotionby chrysarobin. These latter data, when taken together, suggesta role for oxidation at C10 in skin tumor promotion by anthronederivatives. 相似文献
6.
During the period 1950-81, 678 cases of primary hyperparathyroidism were surgically treated at University College Hospital, London. The causes were a single adenoma in 575, two adenomas in 25, carcinoma in 20 (two of which had coexistent adenomas), chief cell hyperplasia in 56, and water clear cell hyperplasia in two. Histological diagnosis is not difficult except in some cases of carcinoma and in a few in which differentiation between recurrent hyperplasia and recurrent carcinoma is exceptionally difficult. In this paper we review all the cases of primary carcinoma of the parathyroid seen during this period to define those pathological features of value in the diagnosis. 相似文献
7.
8.
The turnover rates of adrenaline in the medial preoptic area and mediobasal hypothalamus, areas which, respectively, include the cell bodies and terminals of luteinizing hormone-releasing hormone neurons, have been measured in female rats on pro-oestrus, the day of the preovulatory surge of luteinizing hormone, and on dioestrus, the preceding day. A rise in the rate of turnover was found in the medial preoptic area coinciding with the surge of luteinizing hormone in the late afternoon of pro-oestrus; the rate of turnover at this time was higher than at the same time on dioestrus. No changes in turnover rate were found in the mediobasal hypothalamus within either of these days.The results indicate that the adrenaline-containing projections to the preoptic area may be actively involved in the production of the spontaneous preovulatory surge of luteinizing hormone in rats. 相似文献
9.
In a survey of lymphocyte subpopulations in normal guinea-pig blood, lymph node, spleen, thymus and peritoneal cavity, a considerable overlap was observed between the percentages of C3-receptor bearing lymphocytes (CRL) and of thymus-dependent (T) cells in lymph nodes. Simultaneous rosette-formation reactions with sheep erythrocytes carrying rabbit complement (EAC) and papain-treated rabbit erythrocytes (a T-cell marker) revealed that 20--50% of the lymph node CRL were T lymphocytes. These experiments and others on cell suspensions depleted of Ig-bearing (B) lymphocytes showed that between 8 and 36% of lymph node T cells have complement receptors. The frequency of T-CRL in other lymphoid tissues was lower, representing between 0 and 8% of the T-cell population. The reaction of T-CRL and EAC was not inhibited by EDTA which is known to inhibit the C3 receptor activity on macrophages. 相似文献
10.
The successful use of plasma-sprayed hydroxyapatite (HA) coatings on Ti-alloy implants for implant-to-bone fixation requires strong adherence of the ceramic coating to the underlying metal substrate. In this study, the metal-ceramic interface was evaluated using mechanical, chemical, and structural characterization methods. Evaluations of an HA-coated Ti-6Al-4V implant system using a modified short bar technique for interfacial fracture toughness determination revealed relatively low fracture toughness values. Additionally, conventional tensile bond strength testing indicated much lower values than previously reported. Using high resolution electron spectroscopic imaging, evidence of chemical bonding was revealed at the plasma-sprayed HA/Ti-6Al-4V interface, though bonding was primarily due to mechanical interlock at the interface. This study illustrates the benefits of, and the need for, a multilevel approach to evaluate and improve these plasma-sprayed ceramic-metal substrate interfaces. 相似文献