全文获取类型
收费全文 | 5647篇 |
免费 | 393篇 |
专业分类
6040篇 |
出版年
2021年 | 48篇 |
2019年 | 55篇 |
2018年 | 59篇 |
2017年 | 59篇 |
2016年 | 83篇 |
2015年 | 101篇 |
2014年 | 126篇 |
2013年 | 303篇 |
2012年 | 267篇 |
2011年 | 193篇 |
2010年 | 141篇 |
2009年 | 124篇 |
2008年 | 240篇 |
2007年 | 240篇 |
2006年 | 253篇 |
2005年 | 214篇 |
2004年 | 252篇 |
2003年 | 248篇 |
2002年 | 259篇 |
2001年 | 234篇 |
2000年 | 217篇 |
1999年 | 180篇 |
1998年 | 69篇 |
1997年 | 60篇 |
1996年 | 47篇 |
1995年 | 40篇 |
1994年 | 54篇 |
1993年 | 53篇 |
1992年 | 138篇 |
1991年 | 113篇 |
1990年 | 137篇 |
1989年 | 140篇 |
1988年 | 115篇 |
1987年 | 105篇 |
1986年 | 99篇 |
1985年 | 84篇 |
1984年 | 79篇 |
1983年 | 62篇 |
1982年 | 51篇 |
1981年 | 44篇 |
1980年 | 37篇 |
1979年 | 72篇 |
1978年 | 53篇 |
1977年 | 47篇 |
1976年 | 36篇 |
1975年 | 41篇 |
1974年 | 42篇 |
1973年 | 38篇 |
1972年 | 45篇 |
1970年 | 33篇 |
排序方式: 共有6040条查询结果,搜索用时 0 毫秒
21.
Masafumi Abe Naoya Nakamura Shirou Fukuhara Takamasa Hayashi Keiki Kawakami Kenkichi Kita Toshifumi Kinoshita Toyoro Ohsato Haruki Wakasa 《Virchows Archiv. B, Cell pathology including molecular pathology》1990,59(1):107-113
A new human acute lymphoblastic leukemia (ALL) cell line, designated HBL-3, was established from the bone marrow of a patient
with non-T-ALL. The HBL-3 cell line expressed B4 (CD 19), BA-1 (CD 24) and HLA-DR antigens, but not surface immunoglobulin
(SIg) or cytoplasmic immunoglobulin (CIg). The cell line lacked the common acute lymphoblastic leukemia antigen (CALLA) and
antigenic markers characteristic of T-cell and myeloid cell lineages. The HBL-3 cells had structural rearrangements of both
the homologous chromosome 9s, including a translocation with chromosome 1 which has been reported in a patient with common
ALL. The cell line had rearranged immunoglobulin heavy chain genes but retained germ-line κ light chain genes and germ-line
T-cell receptorβ- and γ-chain genes. The HBL-3 cell line was strongly positive for terminal deoxynucleotidyl transferase (TdT). These findings
indicate that the HBL-3 cell line is derived from the earliest B-cell committed to B-cell lineage. 相似文献
22.
N. Shiratsuki O. Uyama O. Kitada N. Suenaga H. Nakamura M. Sugita Y. Hayashi S. Yamamoto 《Prostaglandins, leukotrienes, and essential fatty acids》1990,40(4):285-289
To study the role of leukotriene C4(LTC4) and the effect of hydrocortisone and aminophylline on plasma LTC4 levels in patients with asthmatic attacks, we measured LTC4 in plasma of 18 asthmatics during a wheezing attack and of 7 normal subjects. Blood samples were obtained before and after treatment with aminophylline and/or hydrocortisone injections. We extracted LTC4 using a Sep-Pak C18 cartridge for the measurement of LTC4 by radioimmunoassay. The plasma levels of immunoreactive LTC4 (i-LTC4) of the normal subjects were 142 +/- 25 pg/ml (n = 7), while those of nonatopic type asthmatic patients with wheezing attacks were 208 +/- 68 pg/ml (n = 15) (p less than 0.01). Before and after treatment with both hydrocortisone succinate (100 mg) and aminophylline (250 mg), 6 asthmatic patients with wheezing attacks had a mean plasma level of i-LTC4 181 +/- 24 and 132 +/- 18 pg/ml (p less than 0.01), respectively. On the other hand, the treatment with aminophylline 250 mg alone increased the i-LTC4 levels from 178 +/- 19 pg/mg to 213 +/- 16 pg/mg (n = 6)(p less than 0.05), while treatment with hydrocortisone succinate 100 mg decreased the i-LTC4 level 0.05 from 284 +/- 99 pg/ml to 249 +/- 85 pg/ml (n = 4)(p less than 0.05). In conclusion, the present study shows that the i-LTC4 level in venous blood of patients with asthmatic attacks is decreased significantly by treatment with hydrocortisone succinate. 相似文献
23.
The three-dimensional structure of the mouse epidermal growth factor (EGF) in solution was studied by comparison of the 1H NMR spectra of alpha EGF (1-53) and beta EGF (2-53, des-asparaginyl 1 form). Using pH dependence of chemical shifts and a two-dimensional difference spectrum, the effect of the N-terminal deletion was investigated based on the complete assignment of the proton resonances. The affected residues were all found to be located exactly in the triple-stranded, beta-sheet core in the N-terminal domain of the EGF molecule. 相似文献
24.
The effects of subcutaneous (s.c.) administration of compound 48/80 (a well known histamine liberator) on latency to thermoalgesic stimulus, hematocrit (Hct) and plasma levels of beta-endorphin-like immunoreactivity (beta-END-LI) were investigated in male rats. The s.c. administration of compound 48/80 in doses ranging from 0.5 to 5.0 mg/kg into the rats produced significant analgesia in the hot plate test and increased Hct in a dose-dependent manner. Concomitant variation was observed between the analgesia and the increase of Hct. This analgesic effect, but not the increase of Hct, was diminished by pretreatment with the opiate receptor antagonist, naloxone (5 mg/kg, s.c.). A significant increase of plasma beta-END-LI was observed by s.c. injection of compound 48/80. Together with a previous finding that compound 48/80 induced-hypovolemia increases the renin release from kidney and then causes water intake in the rats, it is suggested that s.c. administration of compound 48/80 induced analgesia mediated through stimulation of an opioid system, may be closely related to stimulation of the renin-angiotensin system. 相似文献
25.
Reconstruction of chest wall and axilla are performed in 11 patients using a contralateral latissimus dorsi musculocutaneous flap. The entire lattisimus dorsi muscle, including the fascial portion, safely carried an island of skin from the area of the lumbodorsal fascia to the contralateral axilla. The flap was transposed to the defect through a tunnel between the pectoralis major and minor muscles. Most patients who needed reconstruction of the chest wall and axilla had compromised ipsilateral vasculature that prohibited its use in a pedicled flap but had an intact contralateral chest wall, axilla, and thoracodorsal vessels. Therefore, this procedure was performed easily in comparison with a free flap or pedicled omental flap. This is a new, valuable application for the versatile latissimus dorsi musculocutaneous flap. 相似文献
26.
27.
Fumio Hayashi 《Ecological Research》1992,7(2):171-178
The life history of three populations ofProtohermes grandis and two populations ofProtohermes immaculatus (Megaloptera: Corydalidae) was compared. In general, the larvae lived in stream riffles for 2 years and the adults appeared
in summer. Adult body size differed between these closely related species and also between the populations ofP. grandis. Dwarfism occurred inP. immaculatus, a species that is endemic to the small, isolated island, Amami Island. The population ofP. grandis on Yaku Island, located between Amami Island and the mainland Kyushu, had an intermediate body size between that ofP. immaculatus and the mainland population ofP. grandis. Despite being an insular population,P. grandis on Tsushima Island had a similar body size to mainlandP. grandis. In these populations with large adults, some larvae lived in the streams for 3 years. The size distribution of benthic animals,
which are the prey available toProtohermes larvae, differed between the streams studied. The density of large prey was lowest on Amami Island, intermediate on Yaku
Island, and highest on the mainland and Tsushima Island. Different size distributions of available prey may be caused by the
differences of benthic fauna; most of Ecdyonuridae and Ephemerellidae (large mayflies) and Perlidae (large stoneflies) were
not found on Amami and Yaku Islands. Thus, there is a tendency to dwarfism in the populations ofProtobermes inhabiting streams where the density of large prey is low. 相似文献
28.
M Ohta K Ohta H Hara N Itoh Y Itagaki H Nishitani K Hayashi 《Biochemistry international》1991,25(6):1087-1093
We synthesized a peptide designated R8 (amino acid residues 1157-1201) based on the primary structure presumed from the nucleotide sequence of the cDNA clone from the gene for Duchenne muscular dystrophy. Antibody to the synthetic R8 generated by immunization of rabbits was tested on human and mouse skeletal muscle by Western blotting analysis. The antibody reacted with a component of the 400K dystrophin of normal human and mouse skeletal muscles, but not with components of the muscles of Duchenne muscular dystrophy patients and mdx mice. Thus we established that this peptide sequence is in fact missing in the protein product 'dystrophin' encoded by the DMD gene. The antibody may prove useful for the diagnosis of the Duchenne types of muscular dystrophy. 相似文献
29.
30.
A nonisotopic method for determination of the in vivo activities of tyrosine hydroxylase in the rat adrenal gland 总被引:2,自引:0,他引:2
Y Hayashi S Miwa K Lee K Koshimura A Kamel K Hamahata M Fujiwara 《Analytical biochemistry》1988,168(1):176-183
A rapid and reliable method for determination of in vivo activities of tyrosine hydroxylase in the rat adrenal gland is presented. This method involves determining the rate of accumulation of 3,4-dihydroxyphenylalanine (Dopa) in the adrenal gland after decarboxylase inhibition by NSD 1015, using HPLC with electrochemical detection after purification of the acid-deproteinized tissue extract with Bio-Rex 70 columns followed by alumina batch method. Purification of the sample with alumina adsorption alone, a method usually used for purification of catecholamines and Dopa, was ineffective: epinephrine and norepinephrine, which are present in high concentrations, interfered with an accurate determination of Dopa, and dopamine, which is retained strongly on the reverse-phase column, interfered with a rapid analysis. Purification with Sephadex G-10 columns followed by alumina adsorption was also ineffective. After purification with columns of weak cation-exchange resins such as Bio-Rex 70 or Amberlite CG-50 followed by alumina adsorption, most of the epinephrine and norepinephrine was removed and dopamine was eliminated. Thus a rapid and accurate determination of Dopa could be made. Of the two cation exchangers, Bio-Rex 70 was more effective. Accumulation of Dopa in the adrenal gland was linear up to 30 min after administration of NSD 1015 and a plateau was reached with doses over 10 mg/kg. Using this method, we investigated the effects of immobilization stress, reserpine, and hypoxia on in vivo activities of tyrosine hydroxylase in the adrenal gland. 相似文献