全文获取类型
收费全文 | 684篇 |
免费 | 42篇 |
国内免费 | 4篇 |
专业分类
儿科学 | 42篇 |
妇产科学 | 25篇 |
基础医学 | 93篇 |
口腔科学 | 8篇 |
临床医学 | 68篇 |
内科学 | 153篇 |
皮肤病学 | 13篇 |
神经病学 | 38篇 |
特种医学 | 89篇 |
外科学 | 25篇 |
综合类 | 3篇 |
预防医学 | 9篇 |
眼科学 | 18篇 |
药学 | 84篇 |
肿瘤学 | 62篇 |
出版年
2021年 | 11篇 |
2020年 | 7篇 |
2019年 | 12篇 |
2015年 | 7篇 |
2014年 | 6篇 |
2013年 | 16篇 |
2012年 | 20篇 |
2011年 | 17篇 |
2010年 | 11篇 |
2009年 | 11篇 |
2008年 | 12篇 |
2007年 | 15篇 |
2006年 | 13篇 |
2005年 | 22篇 |
2004年 | 10篇 |
2003年 | 13篇 |
2002年 | 17篇 |
2001年 | 17篇 |
2000年 | 21篇 |
1999年 | 27篇 |
1998年 | 19篇 |
1997年 | 22篇 |
1996年 | 25篇 |
1995年 | 9篇 |
1994年 | 12篇 |
1993年 | 20篇 |
1992年 | 19篇 |
1991年 | 19篇 |
1990年 | 26篇 |
1989年 | 23篇 |
1988年 | 17篇 |
1987年 | 16篇 |
1986年 | 20篇 |
1985年 | 20篇 |
1984年 | 6篇 |
1983年 | 13篇 |
1982年 | 9篇 |
1980年 | 7篇 |
1979年 | 9篇 |
1978年 | 11篇 |
1977年 | 7篇 |
1976年 | 8篇 |
1975年 | 6篇 |
1974年 | 8篇 |
1973年 | 9篇 |
1970年 | 8篇 |
1968年 | 10篇 |
1967年 | 7篇 |
1966年 | 9篇 |
1965年 | 8篇 |
排序方式: 共有730条查询结果,搜索用时 15 毫秒
1.
Rats exposed on their first postnatal day to 100% nitrogen for 25 min developed hyperactivity and lower performance in passive avoidance task during development. Administration of MK-801 (0.5 mg/kg i.p.) 1 h before anoxia or (0.25 and 0.5 mg/kg) 1 h after completely reversed this behavioral impairment. Senescent rats (24-26 months) exposed to hypoxia (92% N2 + 8% O2) for 5 h failed in their performance in C.A.R., 30 days later. Pretreatment with MK-801 (1 mg/kg i.p.) completely reversed this impairment. These data suggest that activation of endogenous NMDA receptors produces different behavioral consequences in neonatal and senescent rats and that MK-801 administration close to exposure of animals to anoxia or hypoxia can prevent such damage, thus preventing behavioral impairments in postnatal as well as in senescent rats. 相似文献
2.
Pharmacosomes--a novel drug delivery system 总被引:2,自引:0,他引:2
3.
In two villages of north Ethiopia (Gorgora and Zerema) helminthologic stool analyses were performed and compared with seroimmunologic examinations. Regional difference could be obtained. The infection rate of males was slightly higher than that of females (except Schistosomiasis in Gorgora). Ascaridiasis, Ancylostomiasis and Trichuriasis are probably life-long accompanying parasitoses--they were slightly more frequent in higher than in lower age in Zerema--in contrast to Schistosomiasis which was slightly more frequent in younger people (differences not significant, likely due to the small number of examined persons). Toxocariasis in man is probably not very common in this region. The values of such pilot studies and of seroimmunologic findings for epidemiologic field investigations are discussed. 相似文献
4.
Ralls PW; Johnson MB; Kanel G; Dobalian DM; Colletti PM; Boswell WD Jr; Radin DR; Halls JM 《Radiology》1986,161(2):451-454
FM sonography - a signal-processing technique that uses frequency and phase information as well as amplitude data - shows promise in evaluation of patients with diffuse liver disease. In a prospective blinded review of 37 patients with biopsy-proved liver disease and 42 healthy volunteers, FM sonography was clearly superior to traditional amplitude-based (AM) sonography in distinguishing healthy from diseased subjects. Statistically significant differences were seen in accuracy (FM, 98.7%; AM, 84.8%), sensitivity (FM, 97.3%; AM, 70.3%), and negative predictive value (FM, 97.7%; AM, 78.8%). Our data also suggest that current FM sonographic techniques cannot differentiate among histologic findings associated with different hepatic parenchymal abnormalities. It is unclear, therefore, whether FM imaging can reduce the numbers of patients who require biopsy for diagnosis or the frequency of biopsy procedures in patients with known disease. 相似文献
5.
顾性初 《中国医药工业杂志》1995,(11)
抑制幽门螺杆菌产生的脲酶具有治疗胃炎和消化性溃疡的作用。用酚红指示剂和Berthelot试剂在96孔培养板上检测重组脲酶活性,其灵敏度指标酚红法每mg酶蛋白引起的每分钟吸光度变化。△A为6.9,而Berthelot法每mg酶蛋白引起的每分钟吸光度比值变化△A为313。结果表明用Berthelot试剂检测重组脲酶活性适宜在96孔培养板上大规模筛选天然产物中的脲酶抑制剂。 相似文献
6.
Regina Kirchweger Robert Zeillinger Christian Schneeberger Paul Speiser Genevive Louason Charles Theillet 《International journal of cancer. Journal international du cancer》1994,56(2):193-199
Chromosome 17 is a frequent target during breast-cancer formation and progression. It has been shown to be affected by allele losses at multiple sites, as well as by DNA amplification. Our aim was to delineate a map of the genetic alterations on chromosome 17 in a given set of breast tumors. To this end we analyzed 151 pairs of tumor and cognate lymphocyte DNAs by Southern blotting with 5 RFLP or VNTR probes and by PCR at 8 CA repeat polymorphic loci for LOHs. Moreover, we studied DNA amplification of the evi2, erbB2, thra1, gcsf and rara genes. Data presented here point strongly to the existence of 5 distinct regions of allele losses on chromosome 17:2 on 17p, 3 on 17q. Of the 2 regions on 17p, one involves tp53 while the second is located more distally toward the telomere. LOH was found in 45.9% and 58.8% respectively. The 3 regions on 17q are located: (i) on the proximal portion of the long arm band q21, corresponding to the brcal region; (ii) in a central region defined by the marker D17S74; (iii) on the distal part of 17q (band q25) characterized by losses of the marker D17S24. Each of these regions presented respectively allele losses in 47.5%, 33.3% and 40.8% of the informative tumors. Whereas some tumors presented patterns of LOH consistent with the loss of a complete chromosomal arm or of large portions of the chromosome, a high proportion of the analyzed tumors showed interstitial losses. Amplifications were found in 15% of the tumors and were centered around erbB2. An altered chromosome 17 (bearing an LOH or a DNA amplification) was found in more than 80% of the breast tumor set analyzed here and multiple anomalies affecting this chromosome were often detected in the same sample. 相似文献
7.
Genotype-phenotype correlation for nucleotide substitutions in the IgII- IgIII linker of FGFR2 总被引:6,自引:3,他引:3
8.
Day DJ; Speiser PW; Schulze E; Bettendorf M; Fitness J; Barany F; White PC 《Human molecular genetics》1996,5(12):2039-2048
Steroid 21-hydroxylase deficiency is among the most common inborn errors of
metabolism in man. Characterization of mutations in the 21- hydroxylase
gene (CYP21) has permitted genetic diagnosis, facilitated by the polymerase
chain reaction (PCR). The most common mutation is conversion of an A or C
at nt656 to a G in the second intron causing aberrant splicing of mRNA.
Homozygosity for nt656G is associated with profoundly deficient adrenal
cortisol and aldosterone synthesis, secondary hypersecretion of adrenal
androgens, and a severe form of congenital adrenal hyperplasia (CAH)
characterized by ambiguous genitalia and/or sodium wasting in newborns.
During the course of genetic analysis of CYP21 mutations in CAH families,
we and others have noticed a number of relatives genotyped as nt656G
homozygotes, yet showing no clinical signs of disease. A number of lines of
evidence have led us to propose that the putative asymptomatic nt656G/G
individuals are incorrectly typed due to dropout of one haplotype during
PCR amplification of CYP21. For prenatal diagnosis, we recommend that
microsatellite typing be used as a supplement to CYP21 genotyping in order
to resolve ambiguities at nt656.
相似文献
9.
Perrin C. White Maria-Teresa Tusie-Luna Maria I. New Phyllis W. Speiser 《Human mutation》1994,3(4):373-378
The inherited inability to synthesize cortisol is termed congenital adrenal hyperplasia. More than 90% of cases are caused by 21-hydroxylase deficiency. This syndrome is characterized by signs of androgen excess and often mineralocorticoid deficiency. Steroid 21-hydroxylase (P450c2l) is a microsomal enzyme expressed in the adrenal gland that catalyzes conversion of 17-hydroxyprogesterone and progesterone to 11-deoxycortisol and deoxycorticosterone respectively. In man, this enzyme is encoded by the CYP21 (CYP21B) gene which is located in the HLA major histocompatibility complex along with a pseudogene, CYP21P (CYP21A). Mutations in CYP21 causing congenital adrenal hyperplasia are almost all generated by recombinations between CYP21 and CYP21P. These recombinations either delete CYP21 or transfer deleterious mutations from CYP21P to CYP21, a process termed apparent gene conversion. The degree of enzymatic compromise caused by each mutation is correlated with the clinical severity of the deficiency observed in patients carrying that mutation. © 1994 Wiley-Liss, Inc. 相似文献
10.
We previously reported lymphocyte expression of genes encoding enzymes required for steroid metabolism; however, only 17beta-HSD and 5alpha-reductase showed significant enzyme activity. We now investigate regulation of lymphocyte expression for genes encoding 17beta-HSD and 5alpha-reductase. Cultured human T and B lymphoid cell lines and peripheral blood mononuclear cells were treated with known regulators of steroidogenic gene expression including forskolin, PMA, ionomycin, various steroids, interleukin (IL)-4, and IL-6. Treatment with 10 or 50 microM forskolin resulted in a 20-60% reduction of expression for HSD17B1 (encoding 17beta-HSD I) in T and B lymphoid cell lines and peripheral blood mononuclear cells, although such a change was not observed in the expression of SRD5A1 (encoding 5alpha-reductase I). No significant changes were found when cells were treated for 24 h with various concentrations of PMA or ionomycin. Incubation with 10(-9) to 10(-7) M androstenedione or estradiol increased expression of HSD17B1, while testosterone decreased the expression of this gene. SRD5A1 expression was increased in the presence of 5alpha-DHT although no consistent changes were observed when the cells were treated with testosterone. Other steroids, including dexamethasone, progesterone, and 6-hydroxypregnanolone, produced no effects on expression of either HSD17B1 or SRD5A1. Treatment with 0.1-10 ng/ml of IL-4 or IL-6 also did not effect significant changes in gene expression. These data implicate the involvement of the cAMP-protein kinase signal transduction pathway in regulating lymphocyte expression of HSD17B1. Furthermore, it appears that lymphocyte HSD17B1 and SRD5A1 are regulated to some extent by specific steroids. 相似文献