全文获取类型
收费全文 | 5607篇 |
免费 | 263篇 |
国内免费 | 18篇 |
专业分类
耳鼻咽喉 | 40篇 |
儿科学 | 115篇 |
妇产科学 | 57篇 |
基础医学 | 740篇 |
口腔科学 | 117篇 |
临床医学 | 340篇 |
内科学 | 1120篇 |
皮肤病学 | 163篇 |
神经病学 | 640篇 |
特种医学 | 293篇 |
外科学 | 745篇 |
综合类 | 13篇 |
预防医学 | 312篇 |
眼科学 | 198篇 |
药学 | 512篇 |
中国医学 | 10篇 |
肿瘤学 | 473篇 |
出版年
2022年 | 61篇 |
2021年 | 85篇 |
2020年 | 47篇 |
2019年 | 67篇 |
2018年 | 117篇 |
2017年 | 69篇 |
2016年 | 117篇 |
2015年 | 101篇 |
2014年 | 127篇 |
2013年 | 152篇 |
2012年 | 238篇 |
2011年 | 263篇 |
2010年 | 163篇 |
2009年 | 129篇 |
2008年 | 220篇 |
2007年 | 236篇 |
2006年 | 210篇 |
2005年 | 192篇 |
2004年 | 183篇 |
2003年 | 165篇 |
2002年 | 190篇 |
2001年 | 194篇 |
2000年 | 213篇 |
1999年 | 198篇 |
1998年 | 102篇 |
1997年 | 79篇 |
1996年 | 83篇 |
1995年 | 74篇 |
1994年 | 67篇 |
1993年 | 47篇 |
1992年 | 154篇 |
1991年 | 147篇 |
1990年 | 110篇 |
1989年 | 131篇 |
1988年 | 133篇 |
1987年 | 116篇 |
1986年 | 103篇 |
1985年 | 107篇 |
1984年 | 65篇 |
1983年 | 41篇 |
1982年 | 44篇 |
1981年 | 43篇 |
1980年 | 30篇 |
1979年 | 54篇 |
1978年 | 35篇 |
1977年 | 31篇 |
1976年 | 34篇 |
1974年 | 31篇 |
1973年 | 30篇 |
1970年 | 33篇 |
排序方式: 共有5888条查询结果,搜索用时 15 毫秒
1.
Birth weight on 12,644 singleton infants from 6,196 sibships born in Maryland between 1980 and 1984 were used to estimate the effects of nine maternal and infant covariates on the sibship correlation in birth weight. Assuming a homogeneous correlation across all families, the estimated intraclass correlation was 0.4664 (+/- 0.0099). This high sibship correlation makes it possible to predict, with reasonable accuracy, the birth weight of a child given information on previous sibs, as well as covariates on the mother and/or infant pertinent to a given pregnancy. The reduction in variance associated with incorporating information on the nine covariates used here was approximately equal to that obtained by conditioning on a single previous sib. Testing for heterogeneity in correlation among different groups of families showed that a crude measure of parity (first live birth vs. other), time between births, mother's marital status, and maternal age at the birth of the last child significantly influenced the sibship correlation in birth weight. 相似文献
2.
Mitsumasa Iwata Shunji Izuta Motoshi Suzuki Kiyohide Kojima Yoshihito Furuhashi Yutaka Tomoda Shonen Yoshida 《Cancer science》1991,82(4):433-439
We examined the mechanisms of the inhibition of DNA synthesis by a new platinum compound, (-)-( R )-2-aminomethylpyrrolidine(1,1-cyclobutane-dicarboxylato)-2-platinum(II) monohydrate (DWA-2114R), a derivative of the antitumor drug cis- diamminedichloroplatinum(II) (CDDP), using prokaryotic and eukaryotic DNA polymerases. Preincubating activated DNA with CDDP or DWA-2114R reduced its template activity for prokaryotic and eukaryotic DNA polymerases in a dose-dependent manner. DWA2114R required six times greater drug concentration and two times longer incubation time to show the same decrease of the template activity compared to CDDP. Treatment of primed pUC118 ssDNA templates with the two drugs followed by second-strand synthesis by prokaryotic and eukaryotic DNA polymerases revealed that DWA2114R bound to DNA in a similar manner to CDDP and these adducts blocked DNA elongation by DNA polymerases of eukaryotes as well as of prokaryotes. With these two drugs, the elongations by E. coli DNA polymerase I (Klenow fragment), T7 DNA polymerase and calf thymus DNA polymerase α were strongly arrested at guanine-guanine sequences (GG). Stop bands were also observed at adenine-guanine sequences (AG) guanine-adenine-guanine sequences (GAG) and mono-guanine sequence (G). Calf testis DNA polymerase β was also arrested efficiently at AG, GAG and G, but much more weakly at GG. This pattern was common to DWA2114R and CDDP. 相似文献
3.
Tsutomu Yasutake Daisuke Nagatomo Toshihiko Mizuta Yuichiro Eguchi Takanori Kumagai Keisuke Ario Iwata Ozaki Tateo Kuno Kazuma Fujimoto 《Nihon Shokakibyo Gakkai zasshi》2007,104(12):1752-1757
A 16-year-old man was admitted to our hospital with nausea, general fatigue, and consciousness disturbance along with extreme hyperammoniemia eight days after the onset of symptoms. Familial history and the high concentration of orotic acid in urine lead us to a diagnosis of OTCD. We immediately initiated intensive treatment such as continuous hemodiafiltration and sodium benzoate administration; however, the patient died twelve days after admission. Since OTCD is not so rare and can be found in all ages, it should be considered fundamental for evaluation of hyperammoniemia. This case suggested that for a better prognosis of OTCD patients it is very important to prevent such an onset, and to make an as early as possible diagnosis and start to treatment. 相似文献
4.
The effect of UV irradiation on bovine lens soluble proteins (crystallins) in the presence of tryptophan metabolites was investigated in vitro. The cross-linking of crystallins by UV irradiation was accelerated by kynurenine, 3-hydroxykynurenine, anthranilic acid and 3-hydroxyanthranilic acid. On denaturation of crystallins by photooxidation, alpha-crystallin was characterized by the formation of water-soluble HMW (high molecular weight) protein, while water-insoluble HMW protein was produced from beta- and gamma-crystallin. These HMW aggregates showed cross-linking by non-disulfide covalent bonds. LMW (low molecular weight) peptides were formed by degradation of alpha- and beta-crystallin. 相似文献
5.
H. Iwata T. Otoshi N. Takada T. Murai S. Tamano T. Watanabe Y. Katsura S. Fukushima 《Urological research》1995,23(1):27-32
A series of 8 rat and 16 mouse invasive bladder carcinomas were investigated for the presence of silverstained nucleolar organizer regions (AgNORs) to clarify whether this parameter is applicable to the estimation of their invasive character. With regard to number of AgNORs per cell, neither rat nor mouse carcinomas showed any difference between invasive and noninvasive sites within the same tumor. However, the frequency of cancer cells bearing bizarre dots, irregular in size and shape, was significantly higher at sites of actual invasion. Quantitative data generated using an image analyzer revealed significantly lower values for NOR roundness and significantly larger NOR size in invasive sites than in noninvasive sites in all groups. Double staining for the proliferation marker proliferating cell nuclear antigen (PCNA) and AgNORs was performed on eight rat carcinomas and a close correlation between the two was confirmed. Thus the number of AgNORs in PCNA-positive cells was significantly greater than in PCNA-negative cells. Furthermore, a particularly strong correlation was observed for incidences of PCNA-positive cells and bizarre dots (P<0.01). The quantitative data also demonstrated significant differences in size and shape of dots. It is concluded that AgNORs have diagnostic value for the invasive character of bladder carcinomas. 相似文献
6.
Effects of repeated testing on the incidence of haloperidol-induced catalepsy were investigated in mice. The incidence of catalepsy, evaluated with the forelimbs or hindlimbs placed on a standard horizontal bar, increased in three successive tests in mice injected with haloperidol. Catalepsy was not provoked by repeated testing in animals with saline. In a subsequent study, mice were examined for catalepsy in the forelimbs in the first two trials and then in the hindlimbs. In this procedure, the incidence of catalepsy did not increase with repeated testing. These results suggest that repeated testing increases the incidence of haloperidol-induced catalepsy but does not influence the cataleptogenic potency of the drug. 相似文献
7.
P.F. MORSE D.F. HORROBIN M.S. MANKU J.C.M. STEWART R. ALLEN S. LITTLEWOOD S. WRIGHT† J. BURTON† D.J. GOULD‡ P.J. HOLT§ C.T. JANSEN¶ L. MATTILA¶ W. MEIGEL TH. DETTKE D. WEXLER†† L. GUENTHER†† A. BORDONI‡‡ A. PATRIZI‡‡ 《The British journal of dermatology》1989,121(1):75-90
Gamma-linolenic acid in the form of a particular variety of evening primrose oil (Epogam) has been reported of value in the treatment of atopic eczema. Nine controlled trials of evening primrose oil were performed in eight centres. Four of the trials were parallel and five cross-over. Doctors and patients assessed the severity of eczema by scoring measures of inflammation, dryness, scaliness, pruritus and overall skin involvement. Individual symptom scores were combined to give a single global score at each assessment point. In the analysis of the parallel studies, both patient and doctor scores showed a highly significant improvement over baseline (P less than 0.0001) due to Epogam: for both scores the effect of Epogam was significantly better than placebo. Similar results were obtained on analysis of the cross-over trials, but in this case the difference between Epogam and placebo in the doctors' global score, although in favour of Epogam, failed to reach significance. The effects on itch were particularly striking. There was no placebo response to this symptom, whereas there was a substantial and highly significant response to Epogam (P less than 0.0001). When the improvements, or otherwise, in clinical condition were related to changes in plasma levels of dihomogammalinolenic and arachidoni acids, it was found that there was a positive correlation between an improvement in clinical score and a rise in the fatty acid levels. 相似文献
8.
Fujihiko Iwata M.D. Yoshio Hanawa M.D. Hirotada Takashima M.D. Keichou Shimoura M.D. Youhei Nishibayashi M.D. 《Pediatrics international》1992,34(1):84-86
The pathogenesis and etiology of Kawasaki disease are unknown, but some studies suggest increased genetic susceptibility. The case is presented of an infant with Kawasaki disease whose father suffered from the same illness 21 years previously. The A, B and C loci of the HLA antigens were examined. 相似文献
9.
10.
Ittel TH; Steinhausen C; Kislinger G; Kinzel S; Nolte E; Sieberth HG 《Nephrology, dialysis, transplantation》1997,12(7):1369-1375
BACKGROUND: Developments in accelerator mass spectrometry (AMS) now permit
the determination of femtogram amounts of 26Al in blood and in various
tissues with good precision and free of external contamination. METHODS: In
the present study we used trace quantities of 26Al to investigate the
intestinal absorption and compartmentalization of aluminium in rats with
renal failure (Nx, 5/6 nephrectomy) and in pair- fed controls (C). Single
oral doses of 20 ng 26Al were administered to six animals in each group
and, subsequently, 24-h post-load 26Al was analysed in serum, urine, bone,
liver, and spleen by means of AMS. RESULTS: Serum concentrations of 26Al
were significantly lower in uraemic rats compared to controls, whereas
urinary excretion was comparable (Nx, 7.11 +/- 5.78 pg/day vs C, 9.46 +/-
6.10 pg/day), suggesting a higher fraction of ultrafiltrable serum 26Al in
uraemia. The target tissues of cellular transferrin-mediated 26Al uptake,
liver and spleen, tended to show a larger degree of aluminium accumulation
in controls (0.26 +/- 0.31 pg/g vs Nx, 0.14 +/- 0.10 pg/g and 0.37 +/- 0.27
pg/g vs Nx, 0.25 +/- 0.27 pg/g respectively). In contrast, in bone, a site
of extracellular aluminium deposition, 26Al concentrations were more
elevated in uraemia (1.22 +/- 0.59 pg/g vs C: 0.68 +/- 0.30 pg/g).
Estimated total 26Al accumulation in all measured target tissues was
significantly higher in uraemic rats (28.15 +/- 9.90 pg vs C: 17.03 +/-
7.03 pg) and total recovery of 26Al from tissue and urine was 26.58 +/-
6.74 pg in controls and 35.75 +/- 7.03 pg in uraemic animals, suggesting a
fractional absorption of 0.133% and 0.175% respectively. CONCLUSIONS: Our
data suggest that fractional absorption from a dietary level dose of 26Al
is about 0.13%. Compartmentalization occurs in transferrin-dependent target
tissues such as liver and spleen; however, in quantitative terms
extracellular deposition in bone is more important. Uraemia has a
significant effect on the intestinal absorption and compartmentalization of
aluminium. It enhances fractional absorption and increases subsequent
extracellular deposition of aluminium in bone. However, at the same time
uraemia does not increase transferrin-dependent cellular accumulation of
aluminium in liver and spleen.
相似文献